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Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

This forum is dedicated to discussions pertaining specifically to the Motorola ASTRO line of radios (those that use VSELP/IMBE/AMBE), including using digital modulation, digital programming, FlashPort upgrades, etc. If you have general questions please use the General or Programming forums.

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Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby The Pager Geek » Mon Mar 24, 2003 6:46 am

Well, I was successful in making a Digital MSF5000 (CXB Models) to pass Astro with some bubble-gum and a swiss army knife.

The MSF becomes "transparent" and retransmits whatever it sees, just like the Maxtracs I did. The unregulated community repeater!

The cool part is (if it has a secure board on it) it will pass SecureNet as the repeater is programmed without any problems.

Clear Analog
Clear Analog with PL or DPL (and retransmits the PL or DPL heard)
Secure Analog (Securenet; with secure board)
Astro (VSELP or IMBE)
Secure Astro

It does the above without any problems....

More food for thought... (Cheap P25 repeaters being created. Maxtracs #1, Digital MSF#2.... Analog MSF is next...)

I'm still waiting on the results of the BER with the Maxtracs, these plans are now off to get tested also...

We shall see!!!!
tpg

EDIT 1/12/2012
Never made a cute chart for it.

From my notes:

TLN3189A SSCB (CXB)
Step 1:Program for station for CSQ operation.
Step 2: Remove C8119
Step 3: Run a jumper from J801 Pin5 to Pin6 of U831.
Step 4: While transmitting a digital signal to the input, adjust the output deviation via RSS to 3.0Khz (2.83Khz) on the output.
Step 5: Verify clear analog is approx 4.8Khz

Done.

This will pass everything. Analog, Digital, Securenet (assuming it has a transparent secure board in it), noise, etc. Just like the maxtracs, only it passes 12k securenet where the maxtrac will not.

Good luck
tpg
Last edited by The Pager Geek on Wed Jan 11, 2012 10:30 pm, edited 2 times in total.

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Postby wavetar » Mon Mar 24, 2003 8:07 am

Excellent stuff, Tim. For other people's information, Tim & I have both looked fairly deeply into making an Astro repeater with Astro Spectras. The bottom line is we have both determined if it's not impossible, it's next to it. Not without double-vocoding, at least. The details are long & boring, but if anyone's interested in the findings & reasons, send me a PM.
I guess we'll just have to 'settle' for the Maxtrac & MSF versions!! Beats 30k for a Quantar.

Todd

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Postby RESCUE161 » Mon Mar 24, 2003 9:33 am

Are the down to basics details going to posted on the main batlabs site? I would like to read up on some 'new' stuff. Thanks for bringing the price down for us poor folk...

Scott

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Postby The Pager Geek » Mon Mar 24, 2003 12:47 pm

"Poor folk" including me...

I'll see what I can drum up for the site.... :)

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Postby ExKa|iBuR » Mon Mar 24, 2003 12:53 pm

Am I reading this correctly......


You can make P25 repeat with 2 maxtracs, but NOT 2 astro spectras?


M

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Postby ASTROMODAT » Mon Mar 24, 2003 12:54 pm

One advantage of the MSF5000 is that it's dirt cheap. There was a 450-470 MHz MSF5000 repeater (100 watt) for sale at the local ham fair a few weeks back for $200 asking price. Last I saw, he didn't get any takers, and it was in mint condition. It had all original Motorola cabinet (no scratches, etc.), Motorola station P/S, plus Motorola factory duplexer and isolator (which I would think would be worth $200 on their own right!) If this is a typical price for an MSF5000 repeater, then this might be a good way to go for hams who want to get on IMBE.

Larry

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Postby The Pager Geek » Mon Mar 24, 2003 1:39 pm

NorthYork20:

Yes.. pretty much.

There is two ways of doing this...

1 - The "RICK" method of rerouting audio. Either running analog audio "thru and thru" or double vocoding.

2 - Decoding, reclocking and retransmitting true data. Ultimately a Data Repeater.

The maxtrac and MSF will work fairly well with #1.

The Astro Spectra (it seems) will only be able to do double vocoding. There is no "analog audio" point to steal, nor is there an EASY data line to feed into another astro spectra for reclocking (#2 above.) The DSP is a little too complicated to try to disect for a beneficial experiment.

Plus I don't have a couple of astro spectras to disect to do it either.

Cool huh? Maxtracs as an Astro Repeater? Hehehe...

tpg

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Postby ExKa|iBuR » Mon Mar 24, 2003 2:05 pm

this seems like the obvious....


Can't you just take RX audio from one spectra, and feed it into the mic audio on another spectra, and vice-versa?

I don't know much about spectras so I can't really speak, but wouldn't this work?


M

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Postby The Pager Geek » Mon Mar 24, 2003 2:57 pm

RX Audio. Data or converted audio (decoded voice?)

To decode the data from the receiver and push the converted audio back into another spectra would be double vocoding. No one (that I know of) has tried that yet as a test. I would have if I had 2 spectras collecting dust right now... but....

In theory it would work, however Motorola warns of "degraded audio quality." How much degraded? I dunno. If you have 2 Astro Spectras.. go for it, and let us know!!!!

There is no point in the radio where analog audio of astro data exists, to send to another radio. The only thing I haven't checked yet would be to put the radio in CSQ analog mode, and then go fishing for audio in the radio..... but that's a REAL waste of a good Astro Spectra when even a Maxtrac can do that!!!!

The data lines to try to send from one to the other are very complex involving the DSP. WAY beyond me, 3 parallel lines talking back and forth between the DSP support and DSP.

Hey.. someone try double vocoding and post results!!!!

tpg

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Postby xmo » Mon Mar 24, 2003 4:52 pm

I am sorry we were not able to finish all our double-vocoding tests yet, but here is what we have done so far.

We set up a Quantar and DIU as a conventional (i.e. not trunked) resource connected to a Centracom Gold Elite console that is part of a Smartzone mixed mode system. With this we were able to talk analog to digital and digital to digital through console patch connection.

In this situation the digital to digital pathway is double vocoded. The audio is first vocoded in the initiating radio, then converted back to analog in the Smartzone system's DIU, then digitized at 64K and passed through the Ambassador switch and CEB and out to a BIM where it goes to another [conventional] DIU that vocodes it again and passes it to the Quantar for transmission to the receiving unit where it is converted back to analog a second time.

To avoid any confusion of terminology - the term VOCODER is used here in the 2-way radio context - refering to either the IMBE or VSELP process rather than getting into the semantics and definitions of what terminology is or is not applicable to any other D-to-A or A-to-D process that the audio may undergo in the system.

How did it work? Surprisingly - in the limited time we had - we didn't notice any significant difference. I gave a tester two radios to listen to - both XTS3000's - one on the trunking system and one on the conventional. The trunked pathway was a talkgroup conversation - radio to radio - single vocoded, whereas the conventional radio got the double vocoding described above. They sounded pretty much the same.

What we didn't have time to do yet is see how this set up reacts when one of the radios is starting to get bit errors. We suspect that the audio will degrade faster than normal when that happens.

The other issue is that these tests were for a specific purpose - evaluation of interoperability between a VSELP system and an IMBE system. My associate is setting up (staging at their shop) a system that will allow us to duplicate this test for IMBE to IMBE double vocoding. We will report those results as soon as possible - but we are encouraged by the results so far!

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Postby The Pager Geek » Mon Mar 24, 2003 7:09 pm

Sweeeeeeeeeet!

I just need another Astro Spectra to do it with mobiles for testing.

We shall see!!!

tpg

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Postby ASTROMODAT » Mon Mar 24, 2003 7:17 pm

xmo, my brother says that he has read a Motorola paper done several years ago regarding double vocoding. They used back-to-back ASTRO DIUs, etc. They worked with Bellcore and called in off the street folks (not bumbs) to do subjective listening tests, with the 0 to 5 standard telecom toll scoring routine. I'll see if he can find it. PM me if you are interested.

Larry

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Postby 515 » Tue Mar 25, 2003 7:00 am

I'll put my two cents in...

Double vocoding isn't so bad. The audio is somewhat degraded, but at least you have a "perfect" P25 CAI signal coming out the transmitter. Unfortunately, double vocoding prevents the use of multiple encryption keys, emergency, select call/page, and the use of multiple network access ID's or talkgroups. But unless I had a strong need for one of the above functions, I'd prefer double vocoding over a perfect carrier squelch repeater.

I've played around with a homemade repeater made out of a couple of P25 portables (double vocoding), and it works good. The audio out of the transmitter seems to have more bass in it that the original input audio, but its perfectly readable. I think one could make the audio even better if they put some kind of EQ or other audio processing equipment between the transmitter and receiver and tried to compensate a bit.


A little more sophisticated option is this:

http://www.danelec.com/P25Standard.htm

I've been told that modified Astro Saber boards essentially lie within their P25 transmitter and recever modules. The transmitter board has a different power amp on it, and the recever board has a good helical front end added to it. There's probably some other hardware and software mods to these Astro Saber boards as well...

I believe the first generation of these repeaters were double vocoded, but newer generation ones are vocoded only once. I've tried the newer ones, and they sound just like a Quantar. I've heard somewhere that they might accomplish single vocoding by getting digital voice data from the Astro Saber secure module socket. This kind of makes sense...

Of course I wouldn't think any Network ID, talkgroup, emergency status bit, or encryption key ID's would pass through the audio path of a secure module, so you still wouldn't be able to pass this stuff with this arrangement. But it would be single vocoded. This is in fact how all of the Daniels P25 repeaters I've seen worked--that is, they won't pass encryption, NAC, talkgroup, etc. They may have some very new ones out which have been improved where they do pass this stuff, though.


Has anyone looked at the data going into and out of the Astro secure modules? Is it possible that a couple of "dummy" secure modules could be wired together to pass digital audio from a receiver to a transmitter without any fancy DSP?

If I had some spare Astro radios lying around, that would probably be the first thing I'd look at...

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Postby ASTROMODAT » Tue Mar 25, 2003 10:26 am

The Motorola double vocoding tests (utilizing back-to-back configured DIUs) with Bellcore led subjective listening tests showed some significant problems, with scores as low as 3.0.

Larry

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Postby wavetar » Tue Mar 25, 2003 3:06 pm

515 wrote:Has anyone looked at the data going into and out of the Astro secure modules? Is it possible that a couple of "dummy" secure modules could be wired together to pass digital audio from a receiver to a transmitter without any fancy DSP?

If I had some spare Astro radios lying around, that would probably be the first thing I'd look at...


It was the first place I looked at as well. I did not see any viable signals going to/from the secure module connector, for the Astro Spectra at least. I will double check the detailed service manual schematics for details, hopefully tomorrow as to what exactly goes in/out of those boards & post details.

Todd

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A series Repeators.

Postby Microwave Mike » Tue Mar 25, 2003 4:39 pm

I have a digital 5K repeator with a transparent secure board. Do have a step by step setup to make this a Astro repeator. All rf mods have been made for Ham band use. I was about to install the box up high here in the Phx area, but if it can pass Astro signals I will wait.

Let me know.

MM

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Any further updates?

Postby Motofanatic » Wed Apr 09, 2003 7:57 am

Bump.

Just wondering if there's been any news from The Pager Geek for how he did this with a CXB MSF5k.

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Postby The Pager Geek » Thu Apr 10, 2003 1:31 pm

I'm actually on Revision 2.1 of it... I'll post it once some BER test results come-back... (less that 1% BER that I know of for sure.)

tpg

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Re: Astro Repeater re-visited....

Postby desperado » Wed Jan 11, 2012 2:54 pm

Well, I found this and am now going to resurrect it and add to it.

First off I can't seem to find the info on the conversion. That showing up would be great.
Second off, of course now, MSf's are still cheap and so are Astro Spectra's. That being said, the idea of this conversion needing to be a community repeater style with anything it receiving going back out is not the only way of going about this.

I can see splitting off the receive, so that you have the MSF receiver going into the repeater and feeding the audio over so it will repeat, but with the addition of an ASTRO radio, or at least a receiver controlling the COR so that a NAC or other means of control could be employed so it wasn't CSQ. Of course pulling COR out of a Astro Spectra is not real straight forward, but it's still quite possible and would make for a much nicer configuration for controlling the repeater.


All that being said, is there a detailed set of mods for an MSF to make the conversion to pass Astro?
It's not that I am totally lazy, but I really don't want to drag a 100W MSF into the basement and reinvent the wheel if I can just go grab the controller and solder a few wires on it and then take it back up and align the station in the garage or at the tower site where it will be installed.
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Re: Astro Repeater re-visited....

Postby Astro Spectra » Wed Jan 11, 2012 3:24 pm

Both double vocoding and COR from an Astro Spectra are covered in my humble contribution:

viewtopic.php?f=10&t=80768

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Re: Astro Repeater re-visited....

Postby The Pager Geek » Wed Jan 11, 2012 10:29 pm

desperado wrote:Well, I found this and am now going to resurrect it and add to it.

First off I can't seem to find the info on the conversion. That showing up would be great.
Second off, of course now, MSf's are still cheap and so are Astro Spectra's. That being said, the idea of this conversion needing to be a community repeater style with anything it receiving going back out is not the only way of going about this.

I can see splitting off the receive, so that you have the MSF receiver going into the repeater and feeding the audio over so it will repeat, but with the addition of an ASTRO radio, or at least a receiver controlling the COR so that a NAC or other means of control could be employed so it wasn't CSQ. Of course pulling COR out of a Astro Spectra is not real straight forward, but it's still quite possible and would make for a much nicer configuration for controlling the repeater.


All that being said, is there a detailed set of mods for an MSF to make the conversion to pass Astro?
It's not that I am totally lazy, but I really don't want to drag a 100W MSF into the basement and reinvent the wheel if I can just go grab the controller and solder a few wires on it and then take it back up and align the station in the garage or at the tower site where it will be installed.


I added my notes to the original post in the thread.

tpg
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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby 4n6inv » Sun Jan 15, 2012 3:49 pm

What about narrow band operation?

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Re: Astro Repeater re-visited....

Postby desperado » Mon Jan 16, 2012 3:35 pm

The Pager Geek wrote:
desperado wrote:Well, I found this and am now going to resurrect it and add to it.


I added my notes to the original post in the thread.

tpg



Thanks for adding that in.

Here is my thought and tell me if I am off in la la land or missing something.
What I was thinking is that if an astro radio of some sort was connected controlling the PTT on the repeater, and everything else being equal, then you could eliminate the community repeater style thing and have some control over it coming up. I am going to do the conversion and stick it on a ham pair, but I would rather dedicate it to being Astro only and needing a NAC to used. I figure that an old Astro radio, or even a scanner that will properly decode a NAC would be fine if it can have the COR tapped in it and control the repeater PTT. I am thinking I have a 50/50 splitter at the shop for the VHF band and I was considering using it on the line between the cans and the receiver for the control radio. I'm not sure about the insertion loss however and may be better off to go a different path, but I am not sure what that path would be currently, short of a window filter and a receive multi-coupler.

If anyone has some input on this, it would be welcomed.
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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby Doug » Mon Jan 16, 2012 5:25 pm

How about.....I haven't quite got this figured out yet I'm kind of typing out loud. Program the station to accept the MRTI as a PTT qualifier and set your receive frequency to some obscure frequency and tune the VCO to that frequecy in doing this it will clear up any error codes the station would have, next just attach a dumby load to the SMA and walk away from it. At that point you should be able to interface your other piece of equipment to the MRTI connector, say a scanner or whatever that will react to the NAC code you want if you can find some point that goes the right direction (hopefully low) and attack that to the ptt line attach the audio lines it should react as you want. You may have to build a circuit to sink low enough to trip the PTT on the repeater and you may have to balance some audio lines but what the heck its a place to start and experiment with. If my thinking is right you've taken the msf receiver completely out of the picture and you'll now use whatever as the repeater receiver instead. I'm sure you'll have to go through and make adjustments as needed for deviation and what have you but like I say it may be a place to start
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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby Terriers618 » Tue Jan 17, 2012 12:36 am

Two XTL1500s and a rick..... much cheaper. I hardly notice any double vocoding audio issues when using newer P25 radios with more recent firmware. When I attempted to transmit with an old XTS3000 that hasn't seen a firmware update in almost a decade... well thats a different story. This setup worked beautifully with XTL500s, XTL2500s, XTS2500s, Kenwood TK 5130's and a tait 9100 portable.

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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby desperado » Wed Jan 18, 2012 4:10 am

Doug wrote:How about.....I haven't quite got this figured out yet I'm kind of typing out loud. Program the station to accept the MRTI as a PTT qualifier and set your receive frequency to some obscure frequency and tune the VCO to that frequecy in doing this it will clear up any error codes the station would have, next just attach a dumby load to the SMA and walk away from it. At that point you should be able to interface your other piece of equipment to the MRTI connector, say a scanner or whatever that will react to the NAC code you want if you can find some point that goes the right direction (hopefully low) and attack that to the ptt line attach the audio lines it should react as you want. You may have to build a circuit to sink low enough to trip the PTT on the repeater and you may have to balance some audio lines but what the heck its a place to start and experiment with. If my thinking is right you've taken the msf receiver completely out of the picture and you'll now use whatever as the repeater receiver instead. I'm sure you'll have to go through and make adjustments as needed for deviation and what have you but like I say it may be a place to start
Doug



This I have seen done with Nucleus stations that had VHF TX and UHF RX. There was a maxtrac in the bottom of the cabinet that was UHF and wireline from the prime site. This in its self worked well, but there was then an attempt to simulcast several of these with this configuration, it didn't turn out so hot.
But that is a really good idea none the less for doing this with a single MSF. You could even pull it off with a couple handhelds becasue you are talking in cabinet.
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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby Doug » Wed Jan 18, 2012 6:18 am

My biggest concern would be the selectivity of the receiver. In an area with a lot of stray rf floating around it could be trouble. I had actually thought about doing something like that for a large ham group in the Chicagoland area. It has multiple recieve sites and several talk out sites. My idea was possibly hooking up a maxtrac scanning their several inputs and after a signal capture keying the msf back to their voter, however it hasn't gone much further than just the idea of doing it.
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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby desperado » Wed Jan 18, 2012 5:30 pm

Jason618 wrote:Two XTL1500s and a rick..... much cheaper. I hardly notice any double vocoding audio issues when using newer P25 radios with more recent firmware. When I attempted to transmit with an old XTS3000 that hasn't seen a firmware update in almost a decade... well thats a different story. This setup worked beautifully with XTL500s, XTL2500s, XTS2500s, Kenwood TK 5130's and a tait 9100 portable.



Not sure about cheaper... MSF 5K is a couple hundo. (Mine was free) so then it's just a Astro radio... Unless you have XLT1500's for 200 bucks, if so we need to talk.
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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby Terriers618 » Wed Jan 18, 2012 9:56 pm

My mistake, in my excitement of finally getting two 1500s to work together to create a repeater I misread what equip you were using. Not for 200 but I would imagine the price tag on a used 1500 these days should be around 700-800 bucks? Better than a 20k astro repeater but yes there are cheaper routes.

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Re: Astro Repeater re-visited....

Postby W1HVN » Sat Mar 03, 2012 8:13 pm

desperado wrote:
The Pager Geek wrote:
desperado wrote:Well, I found this and am now going to resurrect it and add to it.


I added my notes to the original post in the thread.

tpg



Thanks for adding that in.

Here is my thought and tell me if I am off in la la land or missing something.
What I was thinking is that if an astro radio of some sort was connected controlling the PTT on the repeater, and everything else being equal, then you could eliminate the community repeater style thing and have some control over it coming up. I am going to do the conversion and stick it on a ham pair, but I would rather dedicate it to being Astro only and needing a NAC to used. I figure that an old Astro radio, or even a scanner that will properly decode a NAC would be fine if it can have the COR tapped in it and control the repeater PTT. I am thinking I have a 50/50 splitter at the shop for the VHF band and I was considering using it on the line between the cans and the receiver for the control radio. I'm not sure about the insertion loss however and may be better off to go a different path, but I am not sure what that path would be currently, short of a window filter and a receive multi-coupler.

If anyone has some input on this, it would be welcomed.



If the receive sensitivity was close to equal, then I'd say you've certainly got something there, assuming a low loss high quality multicoupler is used. The MRTI can be set in line for keying the machine, however I'm not proficient enough on these yet to understand if MRTI keys it, can the internal receiver audio path be utilized, as without a doubt, you want the MSFs ears doing the listening. The only way to test this theory is find an Astro spectra with a tuned/aligned ad hot receiver, use the VRS output as a COR to key, and do some testing. The shame would be 1. It doesn't key but the MSF has a workable signal into it (loss in Astro mobile setup) or 2. The overall rx Sens goes to crap due to loss. I'd say field test without the Astro radio in line (internal controller) and record your results, then make the mod with the Astro radio, and re-evaluate your test being sure to also monitor the signal coming out of the MSF receiver. The results of this will tell us if it's worth exploring and attempting. As a aside, put the Astro in mixed receive mode, this getting Analog and digital to key with a NAC and DPL/PL.

Thanks for updating this btw...good stuff..

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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby Doug » Sun Jan 27, 2013 1:40 pm

First of all thanks to the Pager Geek for his information on passing P25 with an MSF

It's going.......passing the p25 was easy, controlling it was the biggest issue. What I had to do was use an XTL1500 as a second receiver. The MSF is garbage in / garbage out however the xtl isn't. What I had to do was split my receiver cable and run one to the msf and one to the xtl. There are two output lines on the xtl that I've used, one being a channel activity line (goes low which imitates cor) and the other was filtered audio. This is where it gets creative, because all the squelch circuitry is bypassed in the msf it will no longer send an ID, the station keys but sends no audio from the internal controller. My work around was run the cor (channel activity line) to my s-com 7k keying the ptt circuit on the mrti connector, now it's steerable. (correct NAC/PL will key the station) The next hurdle was to get the appropriate ID's to transmitt (remember we're dealing with pure raw unsquelched audio going into the receiver) To over come this I'm using port 2 to regulate a relay,which breaks the receiver line in the msf and switches it to the audio out line on the controller. At ID time the relay switches the audio path and life is good. There's one thing I didn't cover the filtered audio coming from the xtl is fed into my receiver 2 port now you have DTMF control as well.
Hopefully a friend will be stopping by with his 2670 service monitor this week and I'll check and see how close the tolerences are. Sending decoded digital across the room is one thing sending it across the county is another. Stay tunned....
Doug
May the Schwarz be with you.

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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby PETNRDX » Mon Jan 28, 2013 2:21 pm

That is a good way to do it.
I have been playing with the two Maxtrac "pass thru" method myself.
Was planning to use an XTS3000 to be the NAC detector.
Pretty much doing the same thing you have done.
Good ideas there.
Steve K.

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Doug
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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby Doug » Mon Jan 28, 2013 2:54 pm

Trust me it was alot of trial and error and a couple of "OH CRAPS" throw in for good measure. Still waiting to make some test measurements.
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PETNRDX
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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby PETNRDX » Mon Jan 28, 2013 4:39 pm

Fortunately for me I have access to an S412E to get the P25 pass thru really fine tuned, so that was actually pretty easy.
Only need a way to keep ANY carrier from being repeated.
This one actually passes D-Star really well also.
So, NAC "detector", ID and control are my needs.
I guess I will have to go back to work on that.
Steve K.

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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby Doug » Mon Jan 28, 2013 5:20 pm

Right now my biggest worry is what are my loses by adding a receive coupler in the mix. As in any build process there is one thing that you over look and mine was not taking any measurements for sinad before and after installing the coupler. I've not had much luck with pre-amps I'd like to stay away from them if at all possible.
Doug
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Re: Astro Repeater re-visited [MSF SSCB Mod for IMBE]....

Postby cheezhead » Wed Feb 06, 2013 12:36 pm

Has anyone been successfull in finding channel activity on any of the portables? Astro saber xts ect.


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