No longer receiving SDSO on my BCD436

[MisterLongwire]

Tisk tisk gentlemen! my 6 SDS200's and my HP-2 and my 996 and my 346 receive perfectly. The base radios receive perfectly with or without my ST-2- I guess it is my location since I am at the 78 & 15. As for freq's, I guess since I have all loaded it will receive whatever, regardless. I am so stoked though. I get East, Northeast, and South full bars most of the time with the ST-2. With the back of the set antenna I get 3/4 of that. I guess I am just lucky. The portable receives quite well too since I changed to the Diamond antenna, even though it is a bit long but thank god it is flexible

 

[KI6AOK]

Try adding NOISE to your display. That's a useful way to see if you've got RFI on a particular frequency. If NOISE is 2-3 digits, you can normally get a clean digital decode (D-ERROR 0 most of the time, no audible audio garbles) regardless of whether the signal is simulcast. If it's a 4-digit number or higher, that usually indicates RFI from some unwanted signal, or a really weak signal (like less than -105bBm).

Are the RSSI numbers you gave with the Yagi, or an omni antenna?

That's with the Yagi. RSSI is all over the place, but mostly four digits.

 

[jonwienke]

That's with the Yagi.

So without the Yagi, signal is in the -100 to -105dBm range? That's at the lower end of the signal level range the scanners will still decode cleanly. Below -110dBm is ususally where the audio starts breaking up and garbling.

RSSI is all over the place, but mostly four digits.

If you mean NOISE, that's consistent with a signal on the weaker end of the spectrum, if you're talking about the readings during a transmission. On a dead channel, NOISE is usually 5 digits.

 

[KI6AOK]

So without the Yagi, signal is in the -100 to -105dBm range? That's at the lower end of the signal level range the scanners will still decode cleanly. Below -110dBm is ususally where the audio starts breaking up and garbling.


If you mean NOISE, that's consistent with a signal on the weaker end of the spectrum, if you're talking about the readings during a transmission. On a dead channel, NOISE is usually 5 digits.

Sorry, yes, NOISE is four digits during transmissions. With Yagi, RSSI is in the 90s. With discone, RSSI varies depending on freq, but 60-70s (and higher D-ERROR).

 

[jonwienke]

So you're getting a stronger signal with the discone than the yagi. -60dBm is 30dB stronger than -90dBm. Are you near a cell tower by any chance?

 

[KI6AOK]

So you're getting a stronger signal with the discone than the yagi. -60dBm is 30dB stronger than -90dBm. Are you near a cell tower by any chance?

Stronger signal, but high D-ERROR with the discone. Lower signal, but 0 D-ERROR with the yagi properly pointed. There is a cell tower nearby.

 

[jonwienke]

OK that's starting to make sense. What frequency band is the Yagi tuned for? Normally you'd get a stronger signal with the yagi, if it's pointed at the transmitter you're trying to receive. How far exactly is the cell tower?

 

[KI6AOK]

OK that's starting to make sense. What frequency band is the Yagi tuned for? Normally you'd get a stronger signal with the yagi, if it's pointed at the transmitter you're trying to receive. How far exactly is the cell tower?

It's counter intuitive, I know, but the only way I can get a zero D-ERROR is using the yagi. Otherwise, even using different filters, the discone - despite a better RSSI - keeps throwing double and triple digit D-ERROR. Which is why I attribute it to simulcast issues. Maybe it's the nearby cell tower (across the street), but it was never an issue with the mixed mode system I monitored with the discone prior to the P25 RCS NextGen system. I guess it's a case of "your mileage may vary." : ) Thanks for the insight! Very interesting.

 

[Anderegg]

With yagi, our stations SDS200's get -35dBm on West, but the cell tower on our roof creates significant D errors. When we apply the AT feature, RSSI goes down to -108dBm or worse, but D errors drop as well, and we get better digital performance. You may want to try spinning the yagi around at different RCS transmitter sites until you find the best one. On old RCS, we had best signal on Soledad, but now we have to point at Woodson to get best signal strength. And by best one, it may mean the one that might provide less signal stength, but more off axis attenuation to cell towers,, if that makes sense...weaker site in your beam, cell towers behind you in the deaf zone.

Paul

 

[jonwienke]

If you can find a filter that blocks cell freqs, that may be helpful as well.