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APX-7500 Speaker Output

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TX_Shooter
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APX-7500 Speaker Output

Postby TX_Shooter » Mon Aug 25, 2014 8:21 am

I'm trying to find out if there's a way to program the APX-7500 so that the speaker output does NOT mute during TX from the front Microphone, and at the same time find out if the rear (J2) connector outputs a PTT signal when the front microphone is used.

Thanks in advance,
Shooter

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Mon Aug 25, 2014 9:53 am

OK, how do I edit this post? The engineer of our project confused me when he stated the J2 connector on the APX-7500 was to be used. I just looked it up and discovered that the APX is a consolette with Accessory connectors.

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Re: APX-7500 Speaker Output

Postby escomm » Mon Aug 25, 2014 10:52 am

You can't edit the post. Just reply with the updated info.

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Re: APX-7500 Speaker Output

Postby Jim202 » Mon Aug 25, 2014 2:46 pm

TX_Shooter wrote:I'm trying to find out if there's a way to program the APX-7500 so that the speaker output does NOT mute during TX from the front Microphone, and at the same time find out if the rear (J2) connector outputs a PTT signal when the front microphone is used.

Thanks in advance,
Shooter


Not that I am new to radio, but please explain the reason for not wanting the speaker to not mute during transmit? What are you expecting to hear out of the speaker during the time the radio is in transmit?

Jim

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Mon Aug 25, 2014 5:34 pm

Jim,
We tie the radio to a telephone PBX device, then direct both the TX (sidetone) and RX side of the conversation to many 'turrets', but in this case we still need the 'real' operator to use it as a desktop unit as well as the PBX system. The PBX unit will handle the muting of the speaker local to the radio during PTT, but we still need that 'sidetone'.

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Re: APX-7500 Speaker Output

Postby Jim202 » Wed Aug 27, 2014 4:18 am

TX_Shooter wrote:Jim,
We tie the radio to a telephone PBX device, then direct both the TX (sidetone) and RX side of the conversation to many 'turrets', but in this case we still need the 'real' operator to use it as a desktop unit as well as the PBX system. The PBX unit will handle the muting of the speaker local to the radio during PTT, but we still need that 'sidetone'.



Let me see if you can supply the whole picture here to us on the group. Are you using normal dispatch consoles for you different "turrets" as you call them, or are these locations using telephone type remote controls to key and listen to the radio?

Can you describe what your calling the "PBX" unit and how this comes into play with the radio.

A full picture of just what you have would sure help everyone to understand the issue better. Plus try to describe just what your trying to accomplish between the radio connection and the "PBX" connection. I think we all are missing something in the translation of your intentions of how you want it all to function.

Jim

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Re: APX-7500 Speaker Output

Postby Bill_G » Wed Aug 27, 2014 5:02 am

A consolette is nothing more than a mobile in a box with a built in power supply and a wireline interface card. They are not very sophisticated. There isn't a shared audio bus that can route the mic to the spkr during xmit with a mute function you can enable/disable. All consolettes are push-to-talk, let-go-to-listen. You'll have to check this specific product to see if the front and rear PTT lines track each other. In general, they are diode or gate isolated, and independent from each other. I suggest you look at the wireline card to see if carries both sides of the conversation on the rx pair. For intercepting front panel PTT, you'll probably have to build a box that plugs inline with the mic. You might find a programmable line on the accy port that changes state with xmit. You'll have to check.

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Wed Aug 27, 2014 7:28 am

Gentlemen,
I must apologize. At this stage in the game, I can't even confirm which radio our telephone system engineer meant to interface with... he describes it to be a mobile radio, but keeps calling it an "APX".

When I posted my original question, I was under the impression that it was the XTL-7500, but he kept saying "APX", and thus this created my confusion. Methinks he meant to identify the XTL-7500, or possibly the XTL-2500, and not the APX-7500. If it is indeed a consolette, my confidence rises that we can interface per our job design without issue because we've done it many times with the XTL-5000 Consolette. (Why did Motorola change the nomenclature of the consolettes?)

However, if it's the XTL-7500 (a radio that I've not seen yet), and it is similar in interface and function to the XTL-2500 (a radio that I HAVE worked with in recent months), then my original 2-part question still stands because we've seen on the 2500 a base/stand with a speaker directly attached to the radio that mutes during front microphone operation (which would make sense to prevent feedback during TX). It was this muting action, and the lack of knowledgeable people in charge of programming that 2500 radio, that leads me to my quest here on BatBoard.


Let me try to explain what we're doing, and have done with a wide variety of radios world-wide. We install a telephone system complete with its own PBX processor. This system is designed to interface directly with a 2-way radio and present to the user (there can be 1000's) normal TX, RX, and PTT functions, but via analog signals only at the radio (that part needs to be remembered).

However, sometimes we need to 'share' a radio (the actual, physical radio) with an 'entity' (Fire Department in this case for one radio, and police on a few other radios), and that person will not be getting one of our 'turrets' (a 'turret' is a work station with multiple computers, monitors, telephones, radios, and is a 'processor' of information to/from multiple sources... think of NASA launching a shuttle, with its multitude of people needing to share one single radio). Our intention is to route these radio signals so that users can monitor the radio traffic, and any one of them can transmit out over the radio when and if necessary.

But, it doesn't do much good if they can't hear both sides of the conversation from that radio, and in this particular case it's impractical to install a secondary set of radios for this purpose. Hence, my 2-part question in the OP.

Thanks,
Shooter

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Re: APX-7500 Speaker Output

Postby Jim202 » Wed Aug 27, 2014 6:41 pm

TX_Shooter wrote:Gentlemen,
I must apologize. At this stage in the game, I can't even confirm which radio our telephone system engineer meant to interface with... he describes it to be a mobile radio, but keeps calling it an "APX".

When I posted my original question, I was under the impression that it was the XTL-7500, but he kept saying "APX", and thus this created my confusion. Methinks he meant to identify the XTL-7500, or possibly the XTL-2500, and not the APX-7500. If it is indeed a consolette, my confidence rises that we can interface per our job design without issue because we've done it many times with the XTL-5000 Consolette. (Why did Motorola change the nomenclature of the consolettes?)

However, if it's the XTL-7500 (a radio that I've not seen yet), and it is similar in interface and function to the XTL-2500 (a radio that I HAVE worked with in recent months), then my original 2-part question still stands because we've seen on the 2500 a base/stand with a speaker directly attached to the radio that mutes during front microphone operation (which would make sense to prevent feedback during TX). It was this muting action, and the lack of knowledgeable people in charge of programming that 2500 radio, that leads me to my quest here on BatBoard.


Let me try to explain what we're doing, and have done with a wide variety of radios world-wide. We install a telephone system complete with its own PBX processor. This system is designed to interface directly with a 2-way radio and present to the user (there can be 1000's) normal TX, RX, and PTT functions, but via analog signals only at the radio (that part needs to be remembered).

However, sometimes we need to 'share' a radio (the actual, physical radio) with an 'entity' (Fire Department in this case for one radio, and police on a few other radios), and that person will not be getting one of our 'turrets' (a 'turret' is a work station with multiple computers, monitors, telephones, radios, and is a 'processor' of information to/from multiple sources... think of NASA launching a shuttle, with its multitude of people needing to share one single radio). Our intention is to route these radio signals so that users can monitor the radio traffic, and any one of them can transmit out over the radio when and if necessary.

But, it doesn't do much good if they can't hear both sides of the conversation from that radio, and in this particular case it's impractical to install a secondary set of radios for this purpose. Hence, my 2-part question in the OP.

Thanks,
Shooter


OK, first of all you need to get your radio models cleared up. There is the XTL2500, XTL5000 and APX7500 radios that can be used in the consolette radios. The XTL and APX radios are very different radios.

In normal console interfaces, each console should be able to listen to any radio that the console is connected to. When another console talks, the other consoles should be able to hear the transmission that the originating console is making. This is all done via the normal console wiring interfaces.

With that said, you haven't mentioned which vendor radio console system your using. The normal Motorola and Zetron console will allow this monitoring of both RX and TX transmissions. If your using some other brand, then you will have to check with that vendor. Most of the vendors also have a feature called cross muting between multiple consoles so that you don't get feedback between the consoles when one is transmitting. Then the mic gain at each of the consoles comes into play here. If you can hear a pin drop across the room, the radio tech that set the gain up didn't know what they were doing. It's set way too high and just causes problems if the dispatch area is noisy at all.

This is not rocket science to be able to monitor both RX audio and other console TX audio on multiple consoles. The software settings and hard wired connections need to be done with care. It doesn't matter if you have direct connections to the radios or are using a tone remote control package. They all work the same.

Now on the APX consolette interfacing, it's a whole different ball game. Motorola decided to make a major change in the way they controlled the APX series radios. So you need to investigate just how those are connected. The XTL radios used the SB9600 bus to control changing channels (modes), zones and other features in the radio. The APX doesn't use the SB9600 data bus way of doing things. Yes, you can still get the APX consolette to function in a tone remote connection, but they have to be programmed to use it.

Not sure this is what you wanted to hear. But you need to know more about the console equipment you have and what type of connection the radios are using.

Jim

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Re: APX-7500 Speaker Output

Postby gtriever » Thu Aug 28, 2014 2:18 am

The "telephone pbx" thing is what's throwing me here. Other than that, and some strange terminology, it sounds like a typical dispatch console setup using TRC. I can answer one question: Motorola "changed the nomenclature of the consolettes" because the APX7500 consolette replaced the XTL5000 model.

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Thu Aug 28, 2014 4:54 am

OK... since it appears that I'm not going to get an answer to my OP without having to explain the why's and reasons, I very quickly drew up an interface that we've done in the past. If you will, please, substitute the XTL-5000 consolette with EITHER the APX-7500 or the XTL-7500 for the purpose of this discussion.

Whichever MOTOROLA model is not a consolette (XTL or APX 7500), that's the one that I need to figure things out for my original question.

I do realize that the non-consolette model will key differently than the tone remote optioned consolette version, meaning it will require a contact-closure type of switch (or relay) that will connect the radio's PTT pin to the radio's GROUND pin... not a problem with our system. It is this 'switch' that will control the muting of the speaker local to the physical radio in order to prevent feedback during local TX, and it will be accomplished via a pair of relays for Speaker(+) and Speaker(-).

Hopefully this drawing (not to scale) helps to clear things up. For those that are anal about labels, understand that the "LMR 2" and "LMR 3" on the speakers are for two more LMR interfaces NOT DRAWN. (Sometimes I feel as though I'm beating my head against a brick wall when dealing with engineers, and it becomes a sore source of irritation for me.)

As to the "strange terminology", sorry man... telephone and radio... apples and watermelons. And, XTL used to mean "consolette" to us telephone guys, hence some confusion to our world.

Thanks,
Shooter

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Re: APX-7500 Speaker Output

Postby Bill_G » Thu Aug 28, 2014 5:47 am

You could have mentioned you have a CSI Flex interconnect box between the PBX and the radio. This makes sense now. You need a 4 wire to 2 wire bridge so the agency can hear both sides of the PBX conversation. It will connect in parallel to the 4 wire line between the CSI box and the radio. That 2 wire circuit will go by leased line / dry pair to the agency to their tone remote control.

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Thu Aug 28, 2014 6:31 am

Bill_G wrote:You could have mentioned you have a CSI Flex interconnect box between the PBX and the radio.



To be honest, most people I mention it to just give me a blank look, like I'm an alien speaking Zork or something. Also, it is somewhat irrelevant to my OP.

-Shooter

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Re: APX-7500 Speaker Output

Postby Bill_G » Thu Aug 28, 2014 7:37 pm

TX_Shooter wrote:
Bill_G wrote:You could have mentioned you have a CSI Flex interconnect box between the PBX and the radio.



To be honest, most people I mention it to just give me a blank look, like I'm an alien speaking Zork or something. Also, it is somewhat irrelevant to my OP.

-Shooter


I think your first explanation threw a lot us. The drawing helped. Picture, 1000 words, etc. So, will a 2 wire bridge work for you?

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Fri Aug 29, 2014 4:14 am

Bill_G wrote:I think your first explanation threw a lot us. The drawing helped. Picture, 1000 words, etc. So, will a 2 wire bridge work for you?


Bill,
I'm not sure how you're picturing a 2-wire bridge in this particular case.

Allow me to further explain, and then perhaps you can help me to understand your 2-wire bridge concept.

It's been my experience on the XTL-2500 that the rear connector has the following connections:
Pin 20 = Spkr + (Balanced 2-wire (+)) (To local speaker at Radio OR CSI RX+)
Pin 26 = Spkr - (Balanced 2-wire (-)) (To local speaker at Radio OR CSI RX-)
Pin 21 = Aux RX + (Unbalanced (+)) (To CSI RX+ with respect to Radio Ground, typically not used)
Pin 23 = Aux TX + (Mic) (Unbalanced (+)) (To CSI TX+ with respect to Radio Ground)
Pin 16 = Aux PTT (To CSI PTT Relay with respect to Radio Ground)
Pin 15 = Emergency (Needs to see Radio Ground in order to prevent Lockout on the Power Up)
Pin 1 or Pin 14 = Radio Ground

I've actually connected the Speaker +/- to the CSI's RX as a balanced connection in jobs past, rather than using the unbalanced RX audio. This allows for longer wire transmissions, such as over 1000' across telco copper. On average, we've been seeing about 1000' distances. This is mostly due to the department's (fire, police, etc.) physical location, which is in a different building than our equipment. So far (knock on wood) we've been lucky on the unbalanced TX audio having decent quality from the CSI to the radio, but we do have optional amplifiers to install should they become necessary.

In my research on the XTL-7500, I find the same connections, but I'm unsure if they behave the same way as the XTL-2500. One of the things that we noticed on the XTL-2500 was that when the front microphone was used to key the radio, the Speaker output muted, which of course you would normally want that to happen to prevent feedback. In the scenario that has prompted my OP, the physical radio will still need to be used in its normal capacity, while at the same time we need to share its TX and RX capability with our PBX via the CSI, but on our next job, we may be looking at telco copper distances of around 1500-2000'.

Soooooo, as in my OP, I need to find a way to still use this same Speaker Output in order to cover the distance, while not allowing the radio to mute this output internally. I'm hoping that one of the two VIP outputs on the rear connector can be programmed to indicate when the front microphone keys the radio, because I don't think that the AUX PTT on the rear connector changes states if the front microphone is used. If it can, then we'll use that to drive a local (to the radio) muting relay. This way the Speaker audio can still be connected to the CSI, but cutoff to the local speaker, and that will allow our PBX to monitor the TX side of the conversation (provided that sidetone does indeed output during TX... still waiting on an answer to that from my OP).

Thanks,
Shooter

(PS How do I get it set up so that my posts and comments aren't waiting on a Queue Moderator to approve them?)

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Re: APX-7500 Speaker Output

Postby gtriever » Fri Aug 29, 2014 5:48 am

I think we still need to know what it is exactly that you have. There's no such animal as an XTL-7500; the 7500 is an APX series radio. I THINK you're wanting to interface an APX7500 mobile radio to your system... in which case I would probably add a 4-wire Tone Termination Panel to it. That way, it interfaces to the system the same as your XTL series consolettes. And, depending on the vendor, I think most would have a set of app notes (if not a pre-made cable) for the radio to TTP interface.

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Fri Aug 29, 2014 8:02 am

gtriever wrote:I think we still need to know what it is exactly that you have. There's no such animal as an XTL-7500; the 7500 is an APX series radio. I THINK you're wanting to interface an APX7500 mobile radio to your system... in which case I would probably add a 4-wire Tone Termination Panel to it. That way, it interfaces to the system the same as your XTL series consolettes. And, depending on the vendor, I think most would have a set of app notes (if not a pre-made cable) for the radio to TTP interface.


Well then, what actual radio is inside this APX7500 desktop consolette?

If we end up interfacing with a Motorola brand desktop (non-mobile) consolette (pretty much doesn't matter what model at that point, nor which radio is inside of it), then yes, we'll make sure that they have an TRC, and that makes my life a lot easier.

Whichever model is a vehicle-mounted mobile unit that has can be attached to a speaker / base (akin to the HLN6042, if not exactly that specific model), and has the odd 26pin connector on the back... that's what this discussion is about. I won't know for sure what the actual model is until next Wednesday when I finally arrive at the work site and put my own eyes on it. Until then, all that I have to go off of is what the PBX telephone engineer told me as he was the one that did the site survey. (I guess that I should mention that I'm currently several hundred miles away, so it's not like I can just pop on over and take a looksie.)

-Shooter

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Re: APX-7500 Speaker Output

Postby tuckerm » Fri Aug 29, 2014 9:46 am

TX_Shooter wrote:In my research on the XTL-7500,


TX, There is no XTL-7500 radio. There is an APX7500 radio though.

TX_Shooter wrote:(PS How do I get it set up so that my posts and comments aren't waiting on a Queue Moderator to approve them?)


You cannot set that, a Moderator has to approve you being a registered member here first. Then you won't be in a queue.
Schrodinger's Radio: It is simultaneously too loud and too quiet, but you will never know which until someone transmits.

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Re: APX-7500 Speaker Output

Postby Jim202 » Fri Aug 29, 2014 1:19 pm

Your fighting the normal system for how a radio is set up in a tone remote operation functions. Stop trying to use the local mic on the radios connected to the system. Break down and use a desk tone remote for every place that needs to originate a transmission. Then connect your PBX across the 2 wire tone remote connection. Anything that is either being received or transmitted will be on that pair of wires.

The XTL consolette had different control boards in it. I don't have the part number in front of me, but one of them is tone remote control. It might be worth the effort to double check which one you have.

In trying to read this thread and understand just what you have, it leaves a few holes to make sure we all understand just how your keying the radio. I think your saying that tone remote control is what your using, but still not sure.

The other issue that would concern most techs is the level of the audio your blasting down the telco cable to the distant location. Once you go much above a zero db level, you really start to cause cross talk between the cable pairs. This effects other users in that cable. If it was a normal telephone cable, the telephone company would eventually find the source and lift the connection.

As the XTL consolette has been discontinued, if you got your radio recently, the chances are it is a APX7500 consolette. The way to tell the difference is what color is the case? The XTL consolette is that sort of funky cream color Motorola uses. The new APX consolette is a light gray covered case.

The J2 accessory connection on the rear is almost the same between both models.

However, the APX model comes standard with a tone remote function built in. You just need to turn it on with the software if it didn't come out of the plant already set up that way.

Jim

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Re: APX-7500 Speaker Output

Postby gtriever » Sat Aug 30, 2014 3:50 am

TX_Shooter wrote:
Well then, what actual radio is inside this APX7500 desktop consolette?

If we end up interfacing with a Motorola brand desktop (non-mobile) consolette (pretty much doesn't matter what model at that point, nor which radio is inside of it), then yes, we'll make sure that they have an TRC, and that makes my life a lot easier.

Whichever model is a vehicle-mounted mobile unit that has can be attached to a speaker / base (akin to the HLN6042, if not exactly that specific model), and has the odd 26pin connector on the back... that's what this discussion is about. I won't know for sure what the actual model is until next Wednesday when I finally arrive at the work site and put my own eyes on it. Until then, all that I have to go off of is what the PBX telephone engineer told me as he was the one that did the site survey. (I guess that I should mention that I'm currently several hundred miles away, so it's not like I can just pop on over and take a looksie.)

-Shooter


Now we're getting to where my feeble mind can grasp it... :-P Consolettes are designated by the model number of the radio inside them, so the mobile radio you have is an APX7500. Since it's not a consolette, I'd suggest that you add a Tone Termination Panel to it. Then you can control it with TRC which, as you say, makes life a lot easier. You may want to check with CPI Communications for a TTP-1 or a TTP(N) panel, to see if they also have the install notes or a pre-made cable to interface with the APX7500. Sorry for the confusion on my part...

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Sun Aug 31, 2014 4:46 am

gtriever wrote: ...I'd suggest that you add a Tone Termination Panel to it.


Unfortunately, what ever radio or radio type that they have on site, we can not change it nor make recommendations to alter their radio setup at this stage of the game. All that we can do from this point is interface with what they have, or fail. That's why I've been asking these very specific questions (albeit not doing a very good job of identifying the specific radio), so that we can be armed with as much knowledge as possible in order to determine if we'll succeed upon arrival. Our time on site and access to these radios will be limited... that's just the nature of our job.

So, for now, let us assume that there isn't a TRC, and we only have the 26-pin rear connector, and that they have a base / speaker HLN6042. Also, for just the sake of this conversation, let us roll back to a model that I am somewhat familiar with... the XTL-2500. Is it possible to stop it from muting the speaker output during TX (from the usage of the front microphone connection), while at the same time outputting on the rear connector the PTT signal (also from the usage of the front microphone)? If so, how?

(Bear in mind that I do not have the equipment nor rights to alter the programming of any Motorola product... we'll be asking the local radio maintenance shop to handle that part should it become necessary.)

Shooter

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Re: APX-7500 Speaker Output

Postby Jim202 » Sun Aug 31, 2014 5:11 pm

TX_Shooter wrote:
gtriever wrote: ...I'd suggest that you add a Tone Termination Panel to it.


Unfortunately, what ever radio or radio type that they have on site, we can not change it nor make recommendations to alter their radio setup at this stage of the game. All that we can do from this point is interface with what they have, or fail. That's why I've been asking these very specific questions (albeit not doing a very good job of identifying the specific radio), so that we can be armed with as much knowledge as possible in order to determine if we'll succeed upon arrival. Our time on site and access to these radios will be limited... that's just the nature of our job.

So, for now, let us assume that there isn't a TRC, and we only have the 26-pin rear connector, and that they have a base / speaker HLN6042. Also, for just the sake of this conversation, let us roll back to a model that I am somewhat familiar with... the XTL-2500. Is it possible to stop it from muting the speaker output during TX (from the usage of the front microphone connection), while at the same time outputting on the rear connector the PTT signal (also from the usage of the front microphone)? If so, how?

(Bear in mind that I do not have the equipment nor rights to alter the programming of any Motorola product... we'll be asking the local radio maintenance shop to handle that part should it become necessary.)

Shooter



Without getting into the internal circuitry of the radio itself, to the best of my knowledge there is no way to keep from muting the speaker output when the radio goes into transmit. That is just the way all of the Motorola radios are designed to work. Believe your running down the wrong track if that is what your relying on to obtain TX mic audio from the local mic. It just doesn't work that way.

Jim

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Re: APX-7500 Speaker Output

Postby Bill_G » Sun Aug 31, 2014 6:25 pm

+1 what Jim said.

I can't think of any mobiles by any manufacturer that didn't mute the local spkr during xmit. Likewise, I can't think of a mobile that output the local mic hi line to the local spkr line. They don't route the audio that way. The only possible exception would be a mobile with PA capability. Even then, the radio was either xmitting (no mic to spkr) or in public address (no xmit). You couldn't get both. Let's hope your engineering group has some contingencies for you when you go to implement this.

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Re: APX-7500 Speaker Output

Postby gtriever » Mon Sep 01, 2014 3:53 am

Jim and Bill have pretty much summed it up. Without adding a TTP box as part of your interface, I see no way to do what you're wanting to do.

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Re: APX-7500 Speaker Output

Postby Jim202 » Mon Sep 01, 2014 3:54 am

Bill_G wrote:+1 what Jim said.

I can't think of any mobiles by any manufacturer that didn't mute the local spkr during xmit. Likewise, I can't think of a mobile that output the local mic hi line to the local spkr line. They don't route the audio that way. The only possible exception would be a mobile with PA capability. Even then, the radio was either xmitting (no mic to spkr) or in public address (no xmit). You couldn't get both. Let's hope your engineering group has some contingencies for you when you go to implement this.



The bottom line here is a very poor system design. It looks like there are people involved that just don't understand the functionality of a multi control point operation of a radio. This is basic radio dispatch 101. You take a radio, connect it to as many remote control points as you need. All the remote control points can hear both the receive from the radio receiver as well as the transmit audio from which ever remote control originates the transmit audio.

You have done a very poor job of describing the functionality of what ever kluged up system your calling the "PBX" connection. Been in this radio field for many years. been in more dispatch 911 centers than I can remember all over the country. Worked in and on many mobile command vehicles.

With that under my belt, you still haven't made it clear to me and others here just what the goal is that your trying to accomplish with this non standard interface to a radio or consolette. I find it hard why you keep insisting that the speaker output of the radio "MUST CONTAIN THE LOCAL MIC TRANSMIT AUDIO". It just isn't going to happen.

Get over it and figure out how to make your lash up perform. We all have a pride that gets knocked down once in a while. As has been said before, you should back up and evaluate what you have and what your trying to accomplish. It doesn't take a rocket scientist to make a package that works.

If this is a multi channel operation, say so. That is about the only reason I can see for using a local mic on the radio. You would have access to the radio control head sticking out of the consolette. The tone remote control does have the ability to change channels in the radio. With the correct tone remote control you can have up to 8 or 16 channels. Can't change zones in this application with the APX model radio.

Jim

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Mon Sep 01, 2014 4:02 am

Jim202 wrote:... to the best of my knowledge there is no way to keep from muting the speaker output when the radio goes into transmit. That is just the way all of the Motorola radios are designed to work. Believe your running down the wrong track if that is what your relying on to obtain TX mic audio from the local mic. It just doesn't work that way.

Jim

Jim
In as much as I think you're right, I do have to ask the question, "Why does a radio mute the speaker output during TX if there's nothing present on it in the first place?" Meaning, why mute if it isn't necessary? It just seems like a waste of electronics to perform something extra if there wasn't really a need to do so in the first place.

I know of some military radios that do output a sidetone on its RX pins during transmit, so I was hoping this LMR did as well.

I honestly don't think that we're going to get this to work out the way that we need it to, but I still have to try. I was hoping that the programming had some checkbox or setting that could be adjusted to make this happen. For obvious reasons modifying the circuitry of the unit is not an option.

At our first encounter with the 2500's a few months ago, we were tasked to just pick off the speaker feed from the LMR in order to monitor... that's where we discovered this tiny little flaw... only one half of the 'conversation' could be heard. It didn't help that the local radio maintenance guys were, shall we say 'uninformed' on that radio, so I was looking for folks here that had more intimate knowledge and experience for a solution.

Bill_G wrote:Let's hope your engineering group has some contingencies for you when you go to implement this.

Yeah, guess who gets the task of making things work when the engineers promise something that can't be done... yours truly over here. (le sigh)

Shooter

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Re: APX-7500 Speaker Output

Postby Bill_G » Mon Sep 01, 2014 6:03 am

I can only guess why muting the local spkr remains de rigueur in two-way radio design despite modern switching and programming capabilities, but I suspect it is simply lack of demand. No one is pressing for the capability in a mobile radio form factor. There are no common applications for the function in a mobile environment. And, there are base station configurations (ala the consolette) that have both sides of the conversation available on the peripheral interface port.

Mobile radios are inherently push-to-talk, let-go-to-listen. You're either transmitting, or receiving, talking or listening. At one time, the switching in the radio was simply a relay. The majority of the time the radio was in RX mode with power for the receive section (including the audio PA) running through the NC side of a relay. During xmit, the relay switched, applying power to the transmitter section, and thus removed power to the rcvr causing a natural mute to the local spkr. It prevented acoustic feedback when operating on a simplex channel where the TX freq equaled the RX freq. When the freqs were not equal, muting the local spkr prevented bursts of noise from emitting from the spkr during xmit because the high power section of the transmitter may throw off stray local energy that could cause the rcvr to open depending on the freq pairs. The days of using a relay to switch power to the two sections of a mobile radio are behind us, but the basic design concept remains - the receive section is not only muted during transmit, portions of it are quite often unpowered. You have to study the schematics and programming of a specific model to determine what actually happens.

All that said, I think we've agreed what you've been asked to accomplish might not be possible with this model of radio without modification or addition of other devices. They need to provide you with a base station configuration allows you to interface the CSI panel for the telco users (aka telephone interconnect, or telephone patch), *AND* allows a parallel tone control termination panel with associated remote control device for the agency that wants direct control. The only other choice is that agency gets their own stand alone radio that has no physical connection to your work. Then they would participate like any other user in the system, and they would hear both sides without having to modify anything. Your only concern would be isolation between the two antennas on the roof.

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Mon Sep 01, 2014 6:31 am

Bill_G wrote:The only other choice is that agency gets their own stand alone radio that has no physical connection to your work. Then they would participate like any other user in the system, and they would hear both sides without having to modify anything. Your only concern would be isolation between the two antennas on the roof.


Bill,
That's precisely what we had to do our first go'round with the 2500... install a second radio for the CSI only. This gave what we needed (monitoring) plus added the TX functionality as a backup to the original. We got lucky at that location in that a radio plus an antenna were available on the shelf, and they had no issue with installing it for our use. I fear we won't be so lucky on this upcoming and future jobs... so I had to ask my questions 'just in case'.

If it were up to me, I'd be insisting that dedicated LMR's be installed rather than attempting to share a remote radio... it's just more professional that way.

Thanks for everyone's input on this,
Shooter

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Re: APX-7500 Speaker Output

Postby Bill_G » Mon Sep 01, 2014 7:49 am

Yep.

Been there, done that, got the tee shirt in three sizes, and several colors. Good luck.

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Thu Sep 04, 2014 2:22 am

Turns out it is an APX-7500, and we've already proven that the TX audio is currently muted on the speaker output from the rear connector... they thought that they were recording both sides of the conversation using that as a connection. Turns out that they are only getting the RX on the recordings. We'll be looking at this more closely over the next week or so.

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Thu Sep 04, 2014 4:43 pm

Bill_G wrote:Yep.

Been there, done that, got the tee shirt in three sizes, and several colors. Good luck.


I made an updated post to this early today... where did it go?

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Re: APX-7500 Speaker Output

Postby TX_Shooter » Sun Sep 21, 2014 10:59 am

Pin 21 solved our issue once we changed the "Recorder Output" setting to "RX+TX".


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