Problems patching between conventional and trunked BIMs

[Moto_Noob]

I'm doing some work for a customer with a Moto 800 MHz trunked radio system. The system is 12 years old and maintained by the customer.

Their system is maxxed out on trunked BIMs.

I am trying to do some interoperability testing with their system through a conventional BIM.

There is a problem when we talk from the conventional BIM to the trunked BIM. The first .5 seconds of audio gets clipped off. This doesn't happen at the dispatch console. My understanding is that this is a known problem with this radio system. We are looking for ways around the problem at present, but I'm also interested in knowing if there is a way to fix it.

We are looking into donor radios as a work around.

If anyone has any possible fixes or work arounds I would appreciate you following up on this thread or dropping me a line.

 

[N_Jay]

You need to ask where more system mangers, technicians and engineers reside.

http://finance.groups.yahoo.com/group/PrivateWirelessForum

http://finance.groups.yahoo.com/group/SmartNet

http://finance.groups.yahoo.com/group/LMR

https://www.motorola.com/government...ite/Microsite.aspx?Site=en_US/microsites/MTUG

 

[rescue161]

What kind of radios are they using?

 

[DTRS_Master]

1/2 second is pretty long, I think. What conventional radios are you using into the BIM? Sometimes these radios can have slow PL or DPL decoding which causes a delay - but if you're using CSQ, we may want to look elsewhere for some solutions.

 

[im800mhz]

Are you using VOX or COR ? K700 ring a bell ?

 

[Moto_Noob]

This is a Moto 800 MHz trunked system. They use MTS2000 handsets. Originally we were set for VOX. We have since switched to full E&M mode with the addition of an AUX card to our conventional BIM.

I think COR and what I call "full E&M mode" may be the same thing. I don't know what COR stands for, but if that turns on PTT circuit gates between the RADIO and my interop gear then they probably are functional equivalents.

With COR turned on our .5 to .8 seconds of front end audio truncation, what we call clipping, is seriously reduced. We're still getting clipping, but it's down to about .15 to .25 seconds. Much better for use in tactical situations, but still not great.

We're not using conventional radios into the conventional BIM. We're using an E&M card in a Cisco router. This takes the audio and converts it to Voice-over-IP, which we route as normal IP packets.

 

[grem467]

COR = Carrier Operated Relay

check over at the batboard, im sure someone over there in the infrastructure forum can help you get this all sorted.

http://batboard.batlabs.com

 

[SCPD]

We're using an E&M card in a Cisco router. This takes the audio and converts it to Voice-over-IP, which we route as normal IP packets.

Check the specs on the E&M card. Some voice-over-IP systems have a lot of latency in converting the analog voice to packet data. Find out what the expected delay is there. 150 to 250 milliseconds is a long time. That portion should be more like 25 to 50 milliseconds. You're picking up an extra 100 to 200 milliseconds from somewhere. (Yeah, check batlabs, too.)

-rick

 

[im800mhz]

the 300 ms is the best your going to get using a BIM

 

[DTRS_Master]

Moto_Noob - what conventional radio/radios are you using?

 

[Moto_Noob]

I don't know the actual Motorola designation for the conventional radios. I should be able to provide that info next week when I'm back at the customer site.

 

[DTRS_Master]

Okay - please let me know. Thanks!