SDS100 vx BCD436HP: Weak, Simulcast, and Dense RF Drive

Had to go to our distribution center this morning, first thing, and yesterday I assembled my comparative audio kit that lets me record one scanner to left and another scanner to right channel on my PC. So, I thought I'd take the opportunity to make a nice, long recording of both the SDS100 and the BCD436HP monitoring the same site on the same system at the same time.

System is the Fort Worth Regional Radio System. Site monitored is the Northeast Tarrant site, which is widely reported to have some of the worst simulcast problems.

Generally the drive is from Kennedale to Downtown Fort Worth. Up to Roanoke. Then across and down through the middle of the mid-cities (detoured out of my way to make that area) and finally to Irving, just north of DFW airport.

Some of these areas are very weak signal, so neither scanner did perfect, there. Downtown FTW is dense RF. Area of the Mid Cities should be worst for simulcast (and that would be around the 1:20:00-1:40:00 area of the full-length recording).

Had someone do a hard brake in front of me that tossed everything into the floorboard . So, you'll note that the left channel goes bad at the end. I think the audio cable partially unplugged. You can clearly see where this happens in the pic, below.

Left channel (top row of the pic) is BCD436HP. Right channel is SDS100.

I saved two versions of the audio.

• http://info.uniden.com/twiki/pub/PartnerWeb/VideoFolder/NE_Tarrant_Full.mp3 is the full-length real-time version (1 hour 58 minutes)
• http://info.uniden.com/twiki/pub/PartnerWeb/VideoFolder/NE_Tarrant_Compressed.mp3 is a version where I removed all dead air segments, reducing the length to about 19 1/2 minutes.

Here is a pic of what the compressed version looks like in Audacity. The top signal is the BCD436HP, the bottom is the SDS100.


These were each running on their own antenna. The scanners were laying face up in the passenger seat (i.e. real world condition ). BCD436HP had an 800 MHz optimized antenna on it...SDS100 had the stock antenna.

Scanners were in ID Search mode holding on the Northeast Tarrant site.

I’d like to hear some audio from Layer 1/Layer 2 of the FWRRS. My scanners don’t have a great deal of issues with the NETCOM site. My biggest issues lie on Layer 1/Layer 2 of the system. I’d be close to sold if I hear how it performs on those sites and it doesn’t have a great deal of issues.


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I've found L1/L2 performance to be comparable to the Northeast Tarrant site performance (geographic coverage differences accounted for). I'm usually downtown FTW on Saturday morning, but not this weekend (raining for one...helping my sister move for another).

Thanks Paul.

I was wishing I had some wardriving software I could run to plot location vs. audio being received and/or RSSI and Decode Error Rate.

UPMan said:

I was wishing I had some wardriving software I could run to plot location vs. audio being received and/or RSSI and Decode Error Rate.

Click to expand...

Write a script for ZOC (or your favorite terminal emulator program) to pull RSSI, GPS location and decode error rate every few seconds. Then make a .kml file of the data.

UPMan said:

Had to go to our distribution center this morning, first thing, and yesterday I assembled my comparative audio kit that lets me record one scanner to left and another scanner to right channel on my PC. So, I thought I'd take the opportunity to make a nice, long recording of both the SDS100 and the BCD436HP monitoring the same site on the same system at the same time.

System is the Fort Worth Regional Radio System. Site monitored is the Northeast Tarrant site, which is widely reported to have some of the worst simulcast problems.

Generally the drive is from Kennedale to Downtown Fort Worth. Up to Roanoke. Then across and down through the middle of the mid-cities (detoured out of my way to make that area) and finally to Irving, just north of DFW airport.

Some of these areas are very weak signal, so neither scanner did perfect, there. Downtown FTW is dense RF. Area of the Mid Cities should be worst for simulcast (and that would be around the 1:20:00-1:40:00 area of the full-length recording).

Had someone do a hard brake in front of me that tossed everything into the floorboard . So, you'll note that the left channel goes bad at the end. I think the audio cable partially unplugged. You can clearly see where this happens in the pic, below.

Left channel (top row of the pic) is BCD436HP. Right channel is SDS100.

I saved two versions of the audio.

• http://info.uniden.com/twiki/pub/PartnerWeb/VideoFolder/NE_Tarrant_Full.mp3 is the full-length real-time version (1 hour 58 minutes)
• http://info.uniden.com/twiki/pub/PartnerWeb/VideoFolder/NE_Tarrant_Compressed.mp3 is a version where I removed all dead air segments, reducing the length to about 19 1/2 minutes.

Here is a pic of what the compressed version looks like in Audacity. The top signal is the BCD436HP, the bottom is the SDS100.

These were each running on their own antenna. The scanners were laying face up in the passenger seat (i.e. real world condition ). BCD436HP had an 800 MHz optimized antenna on it...SDS100 had the stock antenna.

Scanners were in ID Search mode holding on the Northeast Tarrant site.

Click to expand...

Thank you Paul. Looking forward to getting my hands on this for my testing purpose.

Good info, thanks for posting Paul.

Nice

Paul, am I correct when we hear traffic ONLY on right side(sds100) means the 436 on left completely missing traffic? Correct?

Correct (for this recording). I'll post another one in a while where the answer might be slightly different.

Sounded great to me, Paul. Thanks for going through the trouble!

Mike

Don't say I never give you what you ask for. Here is Fort Worth Regional Radio System Layer 2, same setup, but...


This layer has much more encrypted traffic, and the models are currently handling encryption slightly differently. I couldn't watch the scanners and drive (and really wanted to get home) so some of the silences on one not the other could be due to the scanner sitting on an encrypted channel until the transmission ends. I just got new f/w on them, today, so not completely ingrained what the current behavior is on both. There is certainly a huge difference, even taking that into account. Oh, also this is a busier site, so sometimes the scanners stopped on different channels.


Recording starts in our office parking lot (near belt line and 161) and both were receiving. As I pulled out, 436 seemed to lose the signal. I went into Irving on Belt Line to Northgate, turned Northgate back toward DFW. Near Valley View (where I turned South) 436 started keeping up a bit. But, just from quick glances at the computer from time to time, 436 did not seem to be catching very much most of the time. I took 360 S to I20 then W to 287, ending the recording near Kennedale.


Uncompressed recording is 58 minutes. Compressing out the empty space brought it down to 24 minutes (very busy site).

• Full Recording
• Compressed Recording

And the pic of the compressed recording shows the dramatic difference:

Listening to it, now, there are some blips and bloops where decoding wasn't perfect on the SDS100. But, keep in mind that the signal was so bad the 436 decoded absolutely nothing.

Reading and listening to all this on the new SDS100 is like smelling popcorn at the movies makes you want it more.

UPMan,

Thanks for the effort on this.

While some felt this type of comparison was not helpful or informative, I believe it is very helpful and informative. If you have time and energy to do this on other sites/networks, please try to add to your stack of recordings, I think it can only help people understand how the SDS100 works when compared to other radios like the BCD436HP.

Also agree that the SDS100, or any other radio, may have times where is had difficulty decoding due to signal thresholds and this needs to be understood. Not much different when your cell phone has trouble with a connection.

If you have a small mag mount antenna and a splitter that you could feed equal signal to each radio this would be an ideal comparison.

If anything, antenna-wise the BCD436HP has an unfair advantage, with an antenna that has gain in 700/800 MHz vs a stock antenna, which would help in weak-signal areas. Difference in antenna isn't going to appreciably affect simulcast issues.

Compared to one of the P25 simulcast systems I'm listening to now, this is so much easier to hear! Looking like it's getting ready for prime time!

I wish I had the SDS100 when I went to O'Hare Airport today. My GRE constantly got overloaded and experienced lots of LSM distortion when monitoring StarCom21 in the 700/800 MHz range...

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When looking at the pictures of the audio, the SDS100 seems to have a more compressed audio. Is its AGC working more aggressivly now or is there a simpler explanation that the audio volume out of the earphone jack is different and both scanners need to be set to open squelch and adjust levels to full scale?

/Ubbe