Strange Squawking Sound - G5

[bob550]

Occasionally I will hear a series of two or maybe three very brief squawks at the end of a transmission on my G5. The system I monitor is a P25 trunked system, Albany County. The squawks will only be audible at the end of a transmission and can occur randomly on almost any TGID. The signal level at this point will waver from 1 to 3 bars, but I can't tell you what the RSSI may be at this point. All of my monitoring is done inside my metal-sided house using the upgraded blue-banded antenna. Other than the squawks, the transmission is clear from start to finish. Any idea on the cause?

 

[PapaG]

I hear the same sound on my G5 occasionally while monitoring the Alabama First Responders P25 network. Wonder what it is ?

 

[W8RMH]

I believe that is on the radio system itself when a transmission doesn't come through. I hear it occasionally and the dispatcher will ask the unit to repeat.

 

[bob550]

I believe that is on the radio system itself when a transmission doesn't come through. I hear it occasionally and the dispatcher will ask the unit to repeat.

In my experience, I've never heard a request to repeat a transmission associated with this phenomenon. The squawks only occur at the very end of a call, almost like a roger beep. That said, the P25 system in question isn't always perfect, and perhaps due to terrain challenges, can occasionally produce conversations where a repeat will be requested. Whether or not this has anything to do with it, all my zones and knob positions are programmed with multiple TGID's set to Trunking TG-Scan.

 

[W8RMH]

That could also be the radio transmitting the radio ID.

 

[bob550]

That could also be the radio transmitting the radio ID.

I guess that's possible, but this only happens infrequently and on random TGID's. Also, I've never heard anything like this on my 536HP.

 

[crazyboy]

That could also be the radio transmitting the radio ID.

Not in P25.

 

[JD21960]

This random, shrill squeek was reported about 2 or 3 firmware's ago. I had the same thing out of nowhere before the DMR upgrades and firmware updates. Is your pager updated with the latest stuff? PPS/Firmware 1.2?

 

[W8RMH]

Just throwing out some possibilities.

 

[bob550]

Is your pager updated with the latest stuff? PPS/Firmware 1.2?

Yes.

 

[Uni1]

It is not your G5. My APX and SDS100 get the same squaks on one of the networks here in Dallas. It is random like you say.

 

[bob550]

It is not your G5. My APX and SDS100 get the same squaks on one of the networks here in Dallas. It is random like you say.

So then this does occur on other G5's as well as mine? I think that's my bigger concern, especially not having received a number of me-too replies. I don't experience these squawks on either my Uniden 536HP or 996xt, monitoring the same system.

 

[PapaG]

Unlike the Unication Rep the high pitch squeal that is heard on my G5 occasionally monitoring the Alabama First Responders P25 Network is unique to the G5. This squeal is not heard monitoring this system with my SDS 100, SDS 200, BCD 536, BCD 436. BCD 352P2.

 

[N6ML]

Could someone post a video of the squawking phenomenon ?

Mine makes funny noises sometimes when it's in marginal receive conditions. I've always put it down to decode errors. It does sometimes seem to happen at the end of transmissions. I wonder if sometimes it misses the data indicating the end of a transmission, and tries to decode noise.....

 

[bob550]

Could someone post a video of the squawking phenomenon ?

Mine makes funny noises sometimes when it's in marginal receive conditions. I've always put it down to decode errors. It does sometimes seem to happen at the end of transmissions. I wonder if sometimes it misses the data indicating the end of a transmission, and tries to decode noise.....

A reception issue was my first guess. But the one consistent thing is that these squawks always occur at the end of an otherwise clear transmission.

 

[RFI-EMI-GUY]

A reception issue was my first guess. But the one consistent thing is that these squawks always occur at the end of an otherwise clear transmission.

The repeater system or the receiver are failing to recognize the end of transmission bits and try to process random noise as voice.

 

[bob550]

The repeater system or the receiver are failing to recognize the end of transmission bits and try to process random noise as voice.

What you're saying makes sense. But a quick Google search seems to indicate that stop bits are associated with asynchronous data communication methods. That would make P25 systems asynchronous then?

 

[N6ML]

What you're saying makes sense. But a quick Google search seems to indicate that stop bits are associated with asynchronous data communication methods. That would make P25 systems asynchronous then?

It has nothing to do with stop bits. Those are (were) used in hardware serial communications. P25 uses control data in "units" of various types, including TDUs (Terminator Data Units), which designate the end of a message.

 

[bob550]

It has nothing to do with stop bits. Those are (were) used in hardware serial communications. P25 uses control data in "units" of various types, including TDUs (Terminator Data Units), which designate the end of a message.

So then TDU's serve a similar purpose in signaling the end of a transmission?

 

[N6ML]

So then TDU's serve a similar purpose in signaling the end of a transmission?

Stop bits in serial communication typically occur between each character. In P25, the TDU is a blob of data containing information about the termination of the message. They're operating at different levels.

We're straying a bit from the topic Unication, and are likely to get told to stop by our friendly mods