XPR5550 - lowering squelch threshold level?

[g8tzl2004]

The squelch level on my XPR5550 is too high - on analog mode I am missing weak but readable signals.

This is not the case with my XPR7550 handheld - the squelch opens on a very weak and just copyable signal- which is excellent.

With my XPR5550, a green LED is flashing which I assume indicates that a weak signal is being received but a few more dB is required to open the carrier squelch. I have programmed a front key so that I can manually open the squelch. With my other Motorola stuff I use the tuner software to lower the SQ threshold so that it opens on a real weak signal. However, with the XPR5550 I don't think its possible to actually lower the SQ threshold, other than selecting "normal" or "tight"?

Does anybody know if there is any way to lower the XPR5550 squelch threshold level?

If you can't do it using tuner software is there any firmware mods? I think this was also an issue with the Astro Saber mobiles - you needed to mod the firmware to lower the SQ threshold.

Whats the point of the flashing green LED to indicate a weak signal but the SQ not opening?

Thanks

 

[Mars]

I use the "Normal" squelch for my analog channels. During a weekend coverage test of a new repeater, one of the guys was using a 5550. He had no issues with weak signals not opening his squelch.

The blinking green light is a firmware/configuration problem on Motorola's end. It's a major issue in ALL TRBO radios. I thought it was my plasma TV causing interference on the repeater output (my RX), but no. Even with my outdoor yagi connected to the 5550, and a -128dBm noise floor, it still blinks constantly. Seems there's no fix. I disabled the LED indicator as it's annoying.

I'm sure I could tweak the squelch settings (like I did with the AGC) but it doesn't seem to be a critical issue.

 

[g8tzl2004]

OK on the blinking green light.

On my radio the green light blinks when it is receiving a very weak signal but the signal is not strong enough to actually open the analog carrier squelch. When the weak signal is removed, the green light stops blinking. If you slightly increase the strength of the weak signal the carrier SQ then opens.

If the SQ opened when the green light starts blinking then I would be happy!! Its like the green light is indicating that a signal is being received but the radio thinks that its too weak so will not open the SQ. If you open the SQ manually (monitor button), then you can hear the signal..its very weak but you can understand what is being said.

The threshold at which the carrier SQ closes is good but the threshold at which the SQ opens is just a bit too high for weak signal working ie. once the SQ opens, it will hold a weak signal until its unreadable...but the SQ needs to intially open on a weaker signal for weak signal working. I've compared the 5550 next to my CDM using the same antenna - both have almost identically front end sensitivity but the SQ threshold has been set low on the CDM so although the 5550 is just as sensitive, a weak signal is missed on the 5550 but heard on the CDM.

 

[com501]

Sounds like a hysteresis issue in the squelch threshold or perhaps the DSP threshold is set too high. If it carries it back down into the dirt then it is probably the former. I have a pile of them here, I will play with this a little. What FW are you running?

 

[g8tzl2004]

I'm using R02.05 firmware.

I get the same effect on my 7550 but the green light only blinks on a very very weak unreadable signal. Its like the 7550 SQ opens at +1dBm above the level at which the green light starts blinking ie. on a weak but just copyable signal, while the 5550 SQ only opens at +3dBm above which the green light starts blinking. The level of hysteresis is also much less on the 7550 - the SQ opens and closes with a much smaller swing in signal strength. My UHF 7550 also has a hotter front end than the 5550.

 

[g8tzl2004]

com501 - any luck with reviewing the 5550 SQ?

Once the green light has started blinking (ie. indicating that a weak signal is detected BUT SQ is not yet open), I'm sure you need a stronger carrier to then open the 5555 carrier SQ compared to the 7550 carrier SQ

 

[g8tzl2004]

Does anybody know if later firmware altered the squelch threshold for the 5550 and 4550?

Does anybody else get the same effects - green light starts to blink on Rxing a weak signal but an extra +2/3dB more signal is needed to actually open the carrier SQ?

 

[g8tzl2004]

Does anybody know of firmware 2.4a has lowered the SQ threshold by 2dB so weak but copyable signals are not missed?

One feature of the 2.4a firmware is a change in the RSSI bar graph indication for different signal levels. Earlier firmware seems to be based on minimum dBm thresholds of -117dBm while 2.4a appears to use minimum thresholds of -119dBm...so does this mean that the SQ will open on a 2dB weaker signal?

Thanks

 

[Vocoder]

I don't know what they did specifically, and haven't measured, but the new RSSI graph and associated LED indicators do seem to make more sense in 2.4.

 

[Mototom]

I don't know what they did specifically, and haven't measured, but the new RSSI graph and associated LED indicators do seem to make more sense in 2.4.

That was the first thing I noticed after installing this new firmware.