Astro Saber DPL decode problem

Post by **HumHead** » Sat Apr 27, 2002 10:34 pm

OK- I'm completely stumped here.

My VHF Astro Saber is set up with a whole assortment of stuff, most of which is working just fine. However, one of the channels is a local repeater that uses DPL. While I will swear that things were working just fine until recently (although no one knows exactly how many times a week I "tweak" the programming).

The problem I'm having is this: On the DPL repeater channel (the only DPL channel in the radio) the radio is not unmuting audio properly. It will unmute on the squelch tail when I key the repeater with the Astro in question, but will not open when it is keyed by another radio.

I've been over everything a bunch of times, and I'm at a loss. Here's some of what I've found / tried:

1) I'm certain that I have the frequencies and DPL codes correct. I have a whole bunch of agency HT1250s on my desk, and they are all working properly.

2) The HT1250s are all showing full receive strength from the repeater (located aproximately 5 miles away) on their RSSI displays.

3) If I switch the Astro Saber's receive signalling on that channel to CSQ, it comes in fine with full quieting. (As noted above, I'm 100% certain I'm using the correct DPL code)

4) If I program the output frequency (153.5xx) simplex into a HT1250 and key it on low power (2W) nearby, the squelch opens sporadically (pops on and off). If I put the simplex radio further away, the reception appears to improve (Could I be looking at a desense problem with the DPL here?)

5) If I program another one of our simplex channels, up in the 155MHz range, in with DPL, it seems to work fine.

6) All of the other TPL and CSQ channels are working just fine.

7) The radio has: HOST R05.60.00, DSP I06.04.12, FC 581001-041A00-1, 512K radio

I'm so confused!!!! Any input or help would be greatly appreciated.

Thanks!

Post by **HumHead** » Sun Apr 28, 2002 9:51 am

Thanks Shaun.

Unfortunately, I've already tried both deleting and recreating the personality (both in the same and in a different slot), and reloading the original codeplug that came in the radio. No luck with either.

Post by **HumHead** » Mon Apr 29, 2002 7:08 pm

OK- I don't know if I'm working towards a solution, or just refining the problem, but here's the update:

The problem behaves like a severe attenuation of DPL signals under scan.

The radio will work find if selected on a channel with DPL.

It will not stop on a DPL channel in scan (priority or non-priority) when receiving from the repeater, however, it will stop for a nearby radio running 2w out on simplex.

If the receive squelch type is changed to CSQ, it receives properly during scan.

I took a "look but don't touch" tour through tuner, and didn't see anything odd (Other than the fact that the TX VCO XOver Freq. is set to the XTS3000 default, rather than the Astro Saber default, but that doesn't seem a likely culprit here.)

What the heck is going on here? Help!

Yosh · Post by **Yosh** » Tue Apr 30, 2002 8:04 am

If you have access to lab rss, check to see if someone lowered the detect time for PL under the scan options. I think the default is 300 ms. If it is much lower than the 300 ms, the radio may be detecting carrier but not waiting long enough to decode the DPL.

This wouldn't explain why the closer simplex radio stops the scan, but it is worth a try.

-Yosh

BK117 · Post by **BK117** » Wed May 01, 2002 12:54 pm

Just a guess. Try checking the transmit deviation of the DPL. If it is to high the symptom you described will occure. You host & dsp flash are as high as you can go in that 512k vocoder. Good luck.

Post by **HumHead** » Wed May 01, 2002 1:22 pm

Thanks for the suggestions.

Unfortunately, I don't have access to Lab, just my nice licensed RSS/CPS package. As you noted, it probably wouldn't explain why the radio still works with a local radio anyhow.

The TX DPL deviation being off on the repeater is an interesting thought, although it functions just fine with the rest of our radio fleet (a bunch of HT1250s, CDM & M1225 mobiles, and a few scanners to boot.) Are the Astro Saber known to be more picky about deviation than other radios?

Also, on the Astros, does receive channel width automatically follow the transmit channel width? As I was exploring around, I noticed that there didn't seem to be a way to change the channel width on a receive only channel.

I have access to a (currently unused) spare repeater on another system. Maybe I'll switch it to the same DPL code for a day or two and see if it's a repeater or a radio issue........

BK117 · Post by **BK117** » Wed May 01, 2002 5:19 pm

Yes they did have a DPL problem with radios using your host & dsp in both of the UHF bandsplits. These problems were corected in the mid 90's, however your radio can not be flashed any higher than it already is. Adjusting the DPL deviation of the recieved signal is your best bet (assuming your radio is alligned ie: front end soft pots).
Secondly, channel bandwidth is the same on TX & RX. If you want to change the channel spacing on a RX only channel, you must set recieve only to disabled, then make the changes and set recieve only to enabled again.
Good luck.