Receive Squelch?

[wqpn591]

 I've had my new repeater hardware place for about a week and have been doing some testing around town.

I notice that sometimes when I key up on my mobile and talk that the audio does not come through. But the repeater did receive the signal as I received back the tail after I unkey.

What do you think causes that?

Would think the repeater does decode my CTCSS tone since it does Tx after mobile tx is over.

 

[WyoJoe]

47 minutes ago, wqpn591 said:

 I've had my new repeater hardware place for about a week and have been doing some testing around town.

I notice that sometimes when I key up on my mobile and talk that the audio does not come through. But the repeater did receive the signal as I received back the tail after I unkey.

What do you think causes that?

Would think the repeater does decode my CTCSS tone since it does Tx after mobile tx is over.

 

I'm not sure what you're using for a repeater or mobile radio, but are you using the mobile in close proximity to the repeater?

If so, you may be experiencing desensing of the repeater or the radio. How are you checking to determine if the audio is coming through? Are you listening on another radio while transmitting? If so, it's probably that radio that is experiencing desense.

Since you are hearing the repeater tail, this is what I most suspect in your case.

[WROZ250]

1 hour ago, wqpn591 said:

 I've had my new repeater hardware place for about a week and have been doing some testing around town.

I notice that sometimes when I key up on my mobile and talk that the audio does not come through. But the repeater did receive the signal as I received back the tail after I unkey.

What do you think causes that?

Would think the repeater does decode my CTCSS tone since it does Tx after mobile tx is over.

 

Not sure what you are describing here. 

Are you talking about a 'simplex repeater' (Parrot) or a real, full duplex repeater?

If the latter, are you expecting to hear your transit audio in your mobile, while transmitting? 

Even if you have a dual receive mobile, it is unlikely that you would hear the repeater transmitter as you would likely, assuming a dual receive mobile, de-sense/overload the mobile receiver.  If you are hearing a squelch tail, then your tones settings are probably fine.

That said, the question as asked/described is confusing/unclear.

[wqpn591]

I test on the phone with a listener miles away.

Its a full duplex repeater.

most of the time the audio gets through fine, but sometimes not.

when testing yesterday, I was at the edge of coverage area but since the tail was being received by my mobile unit, figured I was being received.

 

[gortex2]

Most likely desence. Just because you hear the tail does not mean the signal is good enough to pass audio. Who tuned the duplexer ? 

 

You need to give us more info on the setup.

Repeater Model

Feedline type

Antenna Type

Antenna Height ? 

 

[wqpn591]

Repeater is BCR-40U and came with duplexer tuned by them for my freq.

Antenna is commscope DB408-B

Feedline is 25' of LMR400

Antenna is 25' AGL at elevation of 1168'

 

[wqpn591]

I did see a bit of this on my previous design using dual KG1000-G units and a Sinclair duplexer. 

The spray coming out of the Wouxun KG1000-G was so bad that unless I further filtered the Rx side by another 40dB, when keying up the Tx side it would break squelch on the Rx side and get stuck in a loop. Unless I turned the Tx power down to 5W.

 

[gman1971]

yep, another CCR trash transmitter... spewing stuff all over the band.... nothing new.

[gortex2]

So how far away until your getting this his and noise ? Definitely sounds like desence but could just be on the edge of the system. With ot=ut proper test equipment its hard to diagnose. What subscriber are you using to talk back to the system ? Do you have coordinates of the repeater you want to share ? maybe your at the limit.

[wqpn591]

when testing, I'm on a mobile phone with my wife who is at home and I'm about 13 miles away. she is several hundred feed away from repeater unit.

My mobile unit has external roof mount antenna.

Big question is if the repeater receives my signal and can decode the tone well enough to break squelch, why would no audio come through?

Repeater is this on https://mygmrs.com/repeater/5131

Doing some more testing today.

[Radioguy7268]

Unplug your repeater and take it off the air. Try keying up again from the same location. Are you still getting a tail?  The 141.3 Hz "traveler tone" is pretty common, and I'd think that in Texas there some other high site GMRS repeaters on that exact same frequency, also set up with Travel tone.

Another test would be to have a base microphone plugged directly into the mic port of the Bridgecom repeater, and key up on that mic. Can you now hear the transmit clearly at that same distance from the base? If you can, that is a pretty clear indication that your receiver is being knocked out by transmit desense. Kind of common in flat pack duplexers that are being run at more than 10 or 15 watts power.  The "fix" is to lower your transmit power and add a tuned bandpass cavity on your receive frequency - place it between the receive side of the duplexer & the input to your repeater's receiver.

A BCU-40 is not exactly high performance. It's just two ordinary mobile radios in a box with a power supply and a controller.

[wqpn591]

I am actual testing with a different user on the repeater. On tone 250.3 Hz.

Radios inside are Maxon 8402A.

This works way better than the Wouxun KG1000G as that one would not run on max power without a bandpass cavity on the Rx radio side. I'm trying not to do that as it reduces my receive signal by a few db.

One problem I discovered with my mobile unit(Radioddity DB-25G) was the mic gain was set to 30 (out of 120) and voice was garbled. Turned gain off and now voice clarity is much better. could have been mistaken for "nothing coming through" in my previous test. Tested from the same stop today and it seemed to work fine.

Still testing but thanks for the idea to try in simplex mode to check for desense.

[gortex2]

How far do you think its going to talk ? Did you run any propagation studies on this ? I would think an antenna 25' off the ground is only going to give you maybe 10 miles unless its on a mountain top. 

As said above really sounds like desense. 

[wqpn591]

Yeah, did run a prop. Its here https://sites.towercoverage.com/default.aspx?mcid=44585&Acct=134   It is a bit hilly around here so lots of gaps.

Since I'm pretty high in elevation relative to surrounding areas, it covers pretty well. Not a high mountain but reasonable. I've actually talked to a guy on a mobile about 40 miles to the east.

Well, I'm just going to use it as is for now and one day maybe I'll install a small tower to get antenna up a bit more.

 

[gman1971]

Yep, for UHF, for hilly terrain like yours (and mine) antenna height is usually the best way to roll, even 5 feet can make a difference...  Also, good equipment in the base side will go a long way too.

If there are commercial antenna towers nearby, then I would suggest getting at least 1 cavity as well. That will go a LOOOONG way with intermod (not only on RX, but also on TX too) and any potential desense.

G.

EDIT: I would also use RadioMobile, their algorithm usually lowballs the estimated coverage. I would take the average of the two. 40 miles on UHF with only 25' seems like an exception, not the rule. Also, if you plan on using this for personal equipment, for simplex, I would take @gortex2 estimation more like what you'll see, rather than that coverage map. In the end, nothing can replace you going with an RSSI meter logging the different strength signals at different points in the map, then comparing them with a site analysis estimated RSSI strength.