hi all-
We have 10 Informer TARs and we use them with a Whelen/Centralert system. They quit working long ago and I thought it was because they needed narrow banded. I bought the kits and installed the components but they won't activate. We use DTMF codes. They do work in the Monitor Mode and receive on the frequency it's programmed to but in Standby I get nothing. Anyone have any advice or suggestions? The six codes we are using are:
423'1'0'3'2??1
423'1'0'3'2??3
423'1'0'3'2??4
423'1'0'3'2??6
423'1'0'3'2??7
423'1'0'3'2??D
I have researched this to death and I am out of ideas. I already bought the narrow banding kits for all of them so I really don't want to send them in to tech support and cost my company more money.
Thanks
Federal Signal Informer narrow band problems
Moderator: Queue Moderator
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kb4mdz
- Posts: 282
- Joined: Tue Oct 02, 2001 4:00 pm
- What radios do you own?: Too many for the time I have.
Re: Federal Signal Informer narrow band problems
Why didn't you get them working before you bought the narrowbanding kits? Seems like that would have been the better thing to do, rather than push good money into bad radios.
I've got a whole whackful of old VHF informers, didn't know they even could be narrowbanded with a kit; replaced all mine with CDM1250s for 2-tone paging & station alerting. Never got around to testing if they'll operate in a narrowbanded system, with wideband programming.
I've got a whole whackful of old VHF informers, didn't know they even could be narrowbanded with a kit; replaced all mine with CDM1250s for 2-tone paging & station alerting. Never got around to testing if they'll operate in a narrowbanded system, with wideband programming.
Re: Federal Signal Informer narrow band problems
I will say that DTMF tones need to be clean and not distorted or into compression to be decoded correctly.
With that said, you didn't tell us how you are sending the tones through the radio channel. Is it only a base station or are you using a repeater? If your using a repeater, then the repeater must not be compressing the audio also.
In the old days of wide band, using audio in the order of 4.8 KHz deviation, your tones should be around 3 KHz. If your using a repeater, it needs to be set up so that 3 KHz. deviation in will produce no more than 3.5 KHz deviation out. I have not spent time playing with tones on a narrow band system yet, so don't have any feel for recommending the exact point to set the audio levels at yet.
With this said, it is time to get out the service monitor and see just what is going on. I would not be surprised that the radio techs don't have a clue on how to set up a DTMF tone level. Matter of fact, I keep running into equipment that was never set to narrow band operation. Boy does that cause some system problems. Especially if it is the repeater and all the user radios have been changed to narrow band.
Tell us more and what you find with the audio levels on the service monitor.
One other point that needs to be brought up is the audio twist on the DTMF tones. This is caused either by the transmitter or the receiver. If it gets too bad, you will have problems decoding the DTMF tones. The twist is the difference in the audio levels between the high tone and the low tone. Poor telephone cables will cause this. Generally it is not seen on microwave systems unless it also has the audio levels messed up.
With that said, you didn't tell us how you are sending the tones through the radio channel. Is it only a base station or are you using a repeater? If your using a repeater, then the repeater must not be compressing the audio also.
In the old days of wide band, using audio in the order of 4.8 KHz deviation, your tones should be around 3 KHz. If your using a repeater, it needs to be set up so that 3 KHz. deviation in will produce no more than 3.5 KHz deviation out. I have not spent time playing with tones on a narrow band system yet, so don't have any feel for recommending the exact point to set the audio levels at yet.
With this said, it is time to get out the service monitor and see just what is going on. I would not be surprised that the radio techs don't have a clue on how to set up a DTMF tone level. Matter of fact, I keep running into equipment that was never set to narrow band operation. Boy does that cause some system problems. Especially if it is the repeater and all the user radios have been changed to narrow band.
Tell us more and what you find with the audio levels on the service monitor.
One other point that needs to be brought up is the audio twist on the DTMF tones. This is caused either by the transmitter or the receiver. If it gets too bad, you will have problems decoding the DTMF tones. The twist is the difference in the audio levels between the high tone and the low tone. Poor telephone cables will cause this. Generally it is not seen on microwave systems unless it also has the audio levels messed up.
Re: Federal Signal Informer narrow band problems
Federal Signal TAR are the greatest pieces of junk available. I love them to death for what they do, however they are built like complete horse crap. Brand new units, or ones back from repair dead receivers within months, or just loose the ability to decode DTMF for whatever reason.
I would second the use of a service monitor. Most likely if all of them stopped working, than the dispatch may have changed some parameters, and the TAR's are not that forgiving.
The issue we had here is the first digit of the DTMF string was being clipped by tone remote lag, or key up delay in the transmitters at the county dispatch after a console upgrade (not a system under our control), so since your dtmf codes are begin the same, shorten the TAR entered code down to the last 3 or 4 digits, and we have had no issues.
They are touchy, good luck.
I would second the use of a service monitor. Most likely if all of them stopped working, than the dispatch may have changed some parameters, and the TAR's are not that forgiving.
The issue we had here is the first digit of the DTMF string was being clipped by tone remote lag, or key up delay in the transmitters at the county dispatch after a console upgrade (not a system under our control), so since your dtmf codes are begin the same, shorten the TAR entered code down to the last 3 or 4 digits, and we have had no issues.
They are touchy, good luck.
Re: Federal Signal Informer narrow band problems
I would use a service monitor to
a. Verify the alignment of the receivers ...with narrow banding you have less tolerance on frequency and overall performance.
b. verify the DTMF encoding ...should be able to decode that exact sequence from the base station off the air.
c. verify the DTMF decoding on the Informers with the deviation set to 3Khz and then moving down to 1.5khz and see where it fails if at all. Also test this at the lower signal levels like .5uV if not lower.
Given that narrow banding effectively dropped the S/N ratio by 3db you may have to use an external antenna to get back to the same signal quality. ( just speculating )
a. Verify the alignment of the receivers ...with narrow banding you have less tolerance on frequency and overall performance.
b. verify the DTMF encoding ...should be able to decode that exact sequence from the base station off the air.
c. verify the DTMF decoding on the Informers with the deviation set to 3Khz and then moving down to 1.5khz and see where it fails if at all. Also test this at the lower signal levels like .5uV if not lower.
Given that narrow banding effectively dropped the S/N ratio by 3db you may have to use an external antenna to get back to the same signal quality. ( just speculating )
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motorola_otaku
- Posts: 1854
- Joined: Tue Jan 13, 2004 7:03 am
Re: Federal Signal Informer narrow band problems
On 2-tone they will. We have a couple of wideband units that open up just fine receiving a narrowband signal IF the signal is good. A couple of stations that didn't need outside antennas needed them post-narrowbanding.kb4mdz wrote:Never got around to testing if they'll operate in a narrowbanded system, with wideband programming.
Re: Federal Signal Informer narrow band problems
I don't see the need to narrowband a receiver.
Re: Federal Signal Informer narrow band problems
With the original poster not coming back with another comment since Nov 24th, I would have to conclude that he either is in way over his head on this issue, or it no longer matters in resolving the problem.
Jim
Jim
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RADIO43
- Batboard $upporter
- Posts: 743
- Joined: Thu Oct 17, 2002 10:46 pm
- What radios do you own?: 900 MHZ APX4000
Re: Federal Signal Informer narrow band problems
A little off topic here, but has anyone ever configured a Federal Informer into a Motorola Quantar to trigger PTT and play auto over the air via the audio/relay outputs on back of unit? I believe it is possible, just trying to come up with pins and which connector.
In Time of Crisis, You will Not Rise to the Occasion but Rather Default to your Level of Training!
Re: Federal Signal Informer narrow band problems
You could use the DB25 MRTI interface for something that simple. You have to enable the port under station configuration. Or you could use the 25pr connector. Might have to fiddle with the wildcard settings to get it working.RADIO43 wrote:A little off topic here, but has anyone ever configured a Federal Informer into a Motorola Quantar to trigger PTT and play auto over the air via the audio/relay outputs on back of unit? I believe it is possible, just trying to come up with pins and which connector.