is there an Issue with p25 p2?

[Ubbe]

Im sure I will end up using one of these since I'm getting 8-10 dBm rssi better than before on just Normal,

Be careful with that as the scanner will also register the signal strength of the interference. The more interference you get the higher the signal strength, so you probably would want the weakest signal. Use only "Digital Error Count" when evaluating signal quality in digital systems.

/Ubbe

 

[I_Am_Infinite]

Be careful with that as the scanner will also register the signal strength of the interference. The more interference you get the higher the signal strength, so you probably would want the weakest signal. Use only "Digital Error Count" when evaluating signal quality in digital systems.

/Ubbe

Ya for sure i agree, I was watching that and from what I've seen the error rate is pretty similar if not the same on either Normal or Wide Normal the only real difference seemed to be the 8-10 dBm gain in RSSI.

 

[I_Am_Infinite]

I remembered now.. Is firmware 1.10.08 and Sub CPU 1.01.10 the newest versions?

 

[werinshades]

Ya definitely like interference from another frequency, except the frequency seems to be the systems own frequencies when both slots are active.


Thanks, I tried my ass off to get that out right, rewriting and writing etc, hopefully others can understand better to. Ya I hope so to messing with both Wide Norm and Wide Invert Im sure I will end up using one of these since I'm getting 8-10 dBm rssi better than before on just Normal, I'm hoping it will fix that issue to but if its in the system or even in the scanner technology not separating them good when using both slots.

Couple other things on a side note, how come some P25 P2 systems like Starcom dont have the slots like some others, like Starcom is P25 but not TDMA? Do they all eventually switch from regular phase 2 to TDMA phase 2. Ok and forget the couple part, I've now forgot my other question 😂.

Thanks everyone

Starcom sites are all Phase 2 capable, but if any Phase 1 only radios affiliate on the talkgroup, it reverts to Phase 1.

 

[donc13]

I remembered now.. Is firmware 1.10.08 and Sub CPU 1.01.10 the newest versions?

The main 1.10.08 is current
But
My sub version is 1.02.01

it came with that about a year ago.

 

[I_Am_Infinite]

The main 1.10.08 is current
But
My sub version is 1.02.01

it came with that about a year ago.

Thanks I just did my update. My pc screen flashed black a few times while it was downloading the updates that was weird for sure. but all seems good, it works and I didn't brick it so that's good.

 

[JoeBearcat]

The garbled sound indicates interference from another frequency. It would explain what happens if you receive another frequency in the system at that 771.48175 channel. It will help somewhat if you have a longer delay set for the TG's, like 5 sec.

I have a similar problem with an analog trunked system that uses some 30 channels in a 2MHz spectrum. They are all weak at -100dBm to -80dBm and what other frequency I hear on the wrong channel depends of what filter and IFX I use. But I am only substituting one interfering frequency with another. So I am totally unlucky with the frequencies in that system.

/Ubbe

I wonder if this is a 'simulcast' issue where they use the same frequency on two sites, and the scanner is decoding parts of each transmission.

 

[Ubbe]

I wonder if this is a 'simulcast' issue where they use the same frequency on two sites, and the scanner is decoding parts of each transmission.

That would have explained my problem, but I've been to all sites in that UHF system and know it very well how it is built and all the frequencies for the sites and there's only two frequencies that are "doubled". I get this on Marine VHF and VHF Air as well, that a 100% verified frequency are heard some 125KHz and some 250KHz away only 10-20dB weaker. It's not exactly at the channel step but some 2KHz off so it's heard when it's no or weak modulation but when it's properly modulated the squelch close in the SDS100.

I did some tests with the squelch forced open and used a signal generator at a -60dBm signal level and the result where very disappointing.
It was internal mixing going on at almost every 5KHz step, but slightly offset in frequency.

/Ubbe

 

[I_Am_Infinite]

I wonder if this is a 'simulcast' issue where they use the same frequency on two sites, and the scanner is decoding parts of each transmission.

I think what he saying is, that say there's frequency 851.125, and another that's real close in frequency to that, where its picking up both frequencies on 851.125 and causing interference.

What I thought was happening is when my sds200 picked up a transmission it was getting interference from the other slot being used, like when both slots are being used on the same frequency it was causing an interference within the scanner causing the digital error rate to go up above 20 even to 30- n 40s and then the scanner has no audio even with it still open on that frequency.

Its possible though that it just having trouble with the simulcast at times, because its full bars, -80s dBm and error rate will just rise then audio goes garbled and at times just stops even with the talk group still active.

Maybe they can do some testing slots on a frequency and see if its possible within the scanner when both slots are active that they can interfere with each others transmission. Its also possible the I/Q technology isn't perfect and at times it still gets d-error on simulcast.

I know my whistler scanner won't even touch any of the 3 simulcast sites I monitor, its can't even het the data because of the simulcast Interference, so its possible its just the scanner having trouble at times. Its weird cause say like 771.71875 can be coming in perfect no do error then just jump up, the highest d-error I've seen was I. 40s which just causes all audio to stop even with talk group still open... I've even turned the (push/func) button to make it scan again to have it go right back to that same transmission and talk group that just had audio cutout cause do error to be fine. Like it got confused as hell for a second, then me pressing (push/func) making it scan again made it get its crap together again.

That would have explained my problem, but I've been to all sites in that UHF system and know it very well how it is built and all the frequencies for the sites and there's only two frequencies that are "doubled". I get this on Marine VHF and VHF Air as well, that a 100% verified frequency are heard some 125KHz and some 250KHz away only 10-20dB weaker. It's not exactly at the channel step but some 2KHz off so it's heard when it's no or weak modulation but when it's properly modulated the squelch close in the SDS100.

I did some tests with the squelch forced open and used a signal generator at a -60dBm signal level and the result where very disappointing.
It was internal mixing going on at almost every 5KHz step, but slightly offset in frequency.

/Ubbe

The internal mixing is what I thought was happening but instead with 2 different frequencies really close in frequency, it was both slots being active on a single frequency. But as said cud be the scanner is just not perfect and gets confused still at times from simulcast. FBI I don't know but it is somewhat frustrating.

 

[Ubbe]

There are 5 different filter settings and together with IFX you get 10 different options to choose from. Hopefully one of them can be used without hitting any interference frequencies from another transmitter. A couple of the interference frequencies have a sensitivity of -85dBm so its easy to get your monitored frequency distorted from another transmitter several channels away, even more than a MHz.

Video

/Ubbe