NASCAR: SC230 Priority Scanning question

[tvsmike]

Posted this in the Uniden Scanners forum and didn't get a response so I'm hoping maybe somebody checking here could help me:

Hey all--getting ready for racing at Kansas Speedway in a couple weeks and I picked up a SC230 over the holidays to really get serious. It replaces my old Uniden BC95XT. I've spent a few months loading both racing and conventional systems on it and both work fantastic.

So now, I'm getting it really dialed in for the race weekend setting up drivers/officials/media in the group channels and I have all the priority channels set to go.

My Groups Setup:
Groups 1-5: Various favorite drivers that I can turn on and off
Group 6 contains the rest of the field
Group 7 is NASCAR officials
Group 8 is TV
Group 9 is MRN (radio broadcast)

A few of the drivers, NASCAR, and MRN have priority channels. I had a similar setup on the BC95 in a banks setup. The goal is if there is no driver traffic the scanner will sit on MRN or TV (constant feeds) and the scanner is set to priority mode to check those other priority channels every 2 seconds and back to MRN if there is no traffic.

So my problem is this--the scanner is taking at least 3-4 seconds to check the other priority channels. Then its back to MRN for only 2 seconds. Its only scanning about 5 frequencies--it shouldn't take more than a 1/4 of a second to scan those priority frequencies. The BC95 scanning in priority mode was only a hiccup of a scan to check the other frequencies. All my conventional systems are turned off and I'm only operating via the one race system. It also takes just as long when using the Priority Plus feature. That's the part that surprises me even more.

Can anybody help me on what I'm missing? I've got the scanner setup perfect, but its all for not if I can't do the priority scanning efficiently.

Thanks!

-Mike

 

[W6KRU]

Do the priority frequencies have tones assigned?

 

[tvsmike]

Yep, all of them do I believe.

 

[W6KRU]

I'm not sure of all of the effects of the tones but I am pretty sure about a couple of things that could happen. If any of those frequencies are active with the wrong tone during your test, the timeout period for the tone check will have to expire before another channel can be checked.

 

[tvsmike]

Well, the problem is none of the frequencies are active right now since I'm not at the track. The only way I can tell the problem is by turning the squelch up and listening to the static. So I'll get 2 seconds of static and then 4 seconds of no sound while the scanner scans the other priority channels.

 

[W6KRU]

With the squelch turned down, when the scanner checks a priority channel it has to wait for the tone check to timeout before checking the next channel.

My PSR-500 slows down under similar conditions to the point that I can read each alpha label as the frequency is checked for the tone. When the timeout expires the scanner goes on to the next frequency and freezes again.

 

[tvsmike]

Well, that could answer a few questions there for sure. But what I don't understand is that it takes just as long when its scanning only the the priority channels. I mean like 7 frequencies and that's it. 4 seconds is WAY too long. You think its just the tones timing out?

 

[n5ims]

Why do you have the tone programmed in anyway. It's only there to restrict what the scanner picks up and I doubt that there's really anything on the frequencies that you'll want to not listen to. Since the scanner must pause long enough to decode the tones to check to see if it's getting anything that you don't want to pick up it really slows things down, perhaps even causing you to miss short transmissions.

It may be best to not program in the tones so you'll quickly pick up anything on that frequency (so you don't miss something you may be interested in) and speed up the scanning. That way your scanner can quickly see that something's on a desired frequency without the delay of locking onto and decoding the PL tone.

The only reason I can see for keeping a tone programmed in is if there's another group using the same frequency that you don't want to listen to. e.g. a local taxi is on the same frequency with a tone of 123.4 and your driver is there with a tone of 99.2 and you want to eliminate the taxi's transmissions while still picking you your driver's transmissions (not a likely situation since NASCAR has the frequencies licensed and the taxi company wouldn't be issued the same frequency.)

 

[W6KRU]

I just checked the easier to read manual for your scanner and I didn't see any spec for the timeout so I can't say how long it would take for sure. There has to be some delay for each channel though. My PSR-500 for instance waits for 1/10 of a second per channel.

 

[tvsmike]

Yeah, I checked it though--the only hold it has on it is "per system" and technically the race system is the only system I have turned on so it shouldn't take that long. I have a 2 second delay setup for the end of a transmission to make sure I don't miss any quick replies on the channel, but outside of that, that's it.

I still have 2 weeks and thankfully can do all the programming via software so I'll save my current setup, and then create a new one that wipes out all the tones and see what does for scanning.

 

[W6KRU]

Yeah, I checked it though--the only hold it has on it is "per system" and technically the race system is the only system I have turned on so it shouldn't take that long. I have a 2 second delay setup for the end of a transmission to make sure I don't miss any quick replies on the channel, but outside of that, that's it.

I still have 2 weeks and thankfully can do all the programming via software so I'll save my current setup, and then create a new one that wipes out all the tones and see what does for scanning.

The delay I was talking about applies to every channel that has a tone. The scanner has to delay for the tone decoding. Tone decoding isn't instantaneous and the scanner has to wait for the decoding to take place.

 

[tvsmike]

Ah, I gotcha. Didn't know it took so long. Seems as if it was already programmed in, it wouldn't have to "decode" it. But I see what you are saying now.

 

[n5ims]

The "decode" process has to happen each time the scanner stops on a frequency where a tone is programmed. This process can be slow (as you've discovered) since there are several parts to the decode process along with several delays to make sure that something isn't missed and the tone isn't detected falsely. The process goes something like this:

1. The scanner stops on a frequency where a tone has been programmed in. Without a tone, the scanner simply needs to check if that frequency is locked out or not, and can quickly see what needs to be done (resume scan if it's programmed to be locked out or open the speaker if not). Since a tone is programmed, the next checks must be done to see what to do next.

2. Wait until a tone has been detected or the associated time-out value is reached. This time-out may be as much as half a second. If the time-out timer expires, resume scanning (no tone detected), otherwise keep checking.

3. A tone has been detected, but it may be a false detection due to random noise or voice just happened to hit a valid frequency. Keep detecting the tone for a length of time to verify it's a valid tone (often 1/10 of a second or so of solid detection is required to validate the tone). If tone isn't valid, continue with step 2. If tone is valid, continue checking.

4. Compare the detected tone with the programmed value. If it doesn't match, resume scanning. If it matches, check lock-out value and act accordingly.

There is also a process for when the tone drops, but that isn't necessary for this discussion.

Your scanner may not follow this exact process, but it is close to how many scanners and radios will do so. This is to make sure that the tone is properly detected and not turned on by random noise or voice artifacts. If the detection process was a simple tone's there/tone's not there check without the delays, it would miss transmissions where the scanner picks up the call very early prior to the tone being passed or activate on transmissions where a voice artifact happens to hit the tone's audio frequency for just a split second.

 

[tvsmike]

Fantastic way of explaining it. Will do some checking on it tomorrow--thanks so much for the detailed message.

 

[nanZor]

So my problem is this--the scanner is taking at least 3-4 seconds to check the other priority channels. Then its back to MRN for only 2 seconds. Its only scanning about 5 frequencies--it shouldn't take more than a 1/4 of a second to scan those priority frequencies.

This could also be a visual trick if you aren't hearing any real transmissions - the display on my unidens when peppered with only a handful of frequencies/systems/groups etc will actually seem a bit slower than what is going on under the hood - otherwise everything would be a massive blur.

For a quick test, you can check the timing better if you can get hold of an FRS radio, and program those freqs / tones into your systems temporarily and key up and see just how long it takes for it to come around.

 

[tvsmike]

I appreciate the response hertzian, but I only have one system scanning and that's it, so the top line reads "Sprint Cup" while the 2nd line is scrolling "scan" during the scan obviously. So its not quite that. But it does looks as if DDan has hit my problem on the head. I went back and locked out the tones and that seems to have solved the problem. I haven't completely verified it yet, but its looking more and more like that is the problem.

Appreciating the help nonetheless!!

-Mike