What factors affect HomePatrol scan speed?

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B-One

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Greetings All,

Am I correct that a "channel" is the same as a TGID?

Also, am I correct on the following? The radio scans the frequencies, stops on an an active frequency and then searches the database for the correct TGID. If this is how the radio operates, is the only factor that affects scan speed the number of sites monitored? Does the number of TGIDs or Channels in the data base have any affect on scan speed?

I have been fooling around with my HP. Currently I am monitoring three P25 sites in my favorites list. Each site has five frequencies. I have the TGIDs for all of the neighboring counties and state agencies in my Favorites List. Currently, my radio is monitoring in excess of 700 channels.

Thanks all for your help.
 

phask

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Number of TG in a list makes no difference. Paul (UPMAN) posted this somewhere as someone will argue the point :)

Number of sites do affect it. If using a FL limit it to as few as useful,if mobile with location enabled and a GPS and using FL - revise range on sites to something realistic for your setup.

If using entire db - endure slow scanning :)
 

phask

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Also the channel delay and system rescan delay can change the scan speed.

I don't think a HP has system rescan delay. Just the new ones - of course now we are getting people referencing the HP-1 and new ones as home patrols :)
 

B-One

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Exactly the info I was seeking! Thanks for the responses.
 

k9jus

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New to the hp1. In reference to how slow it scans in a p25 system, would it help if a person chose the closest site to you and lock out all of the rest of the sites? Has anyone ever tried this?.
 

phask

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Read 3 or 4 posts above ...

If you can get all you want with the one, yes.

ie less sites are better for speed. I need to monitor 3 sites to cover waht I want to hear.
 

k9jus

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Is there an easier was to block out all the other sites than going through each channel. I thought if i chose advanced from the name of the system, i would be able to do it from there but no luck
 

lep

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Greetings All,

Am I correct that a "channel" is the same as a TGID?

Also, am I correct on the following? The radio scans the frequencies, stops on an an active frequency and then searches the database for the correct TGID. If this is how the radio operates, is the only factor that affects scan speed the number of sites monitored? Does the number of TGIDs or Channels in the data base have any affect on scan speed?.
The radio does not "scan the frequencies" since you are talking about a Trunking system (or channels would not be TGIDS). The control channel is always transmitting, so the radio "listens" to the c.c. for a Channel Grant message, it compares the TGID with memory to see if that is a channel you want to hear, if so, it changes frequency to hear that TGID. The cycle time to hear the digital messages on the c.c. is around 2 seconds. Assuming you can monitor what you want from a single site, it would seem faster to limit your c.c. sites to that one. The number of TGIDs is not relevant. The number of sites is. The time to complete the round of digital messages is not adjustable.
 

DaveIN

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I don't think a HP has system rescan delay. Just the new ones - of course now we are getting people referencing the HP-1 and new ones as home patrols :)
True all three radios are HP. There is a delay between the systems on the HP-1, however no way to access it. :(
 

k9jus

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So is there a way to limit the sites to just one that the talkgroups scan for an entire system?
 

N0UDG

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Greetings All,

Am I correct that a "channel" is the same as a TGID?

Also, am I correct on the following? The radio scans the frequencies, stops on an an active frequency and then searches the database for the correct TGID. If this is how the radio operates, is the only factor that affects scan speed the number of sites monitored? Does the number of TGIDs or Channels in the data base have any affect on scan speed?

I have been fooling around with my HP. Currently I am monitoring three P25 sites in my favorites list. Each site has five frequencies. I have the TGIDs for all of the neighboring counties and state agencies in my Favorites List. Currently, my radio is monitoring in excess of 700 channels.

Thanks all for your help.

Numerically sorting frequencies (high to low or low to high) on conventional systems can increase the scanning rate so I asked if sorting the TGIDs or frequencies in a trunked system would do the same.
Here is UPMan's Reply:

"The rate at which a trunked system "scans" is entirely dependent on the control channel data. During trunked scanning, the scanner sits on a single frequency (the control channel) and watches for channel grants and channel updates, comparing those to the TGIDs you have programmed. Sorting the TGIDs won't make this happen any faster."
UPMan

Since I do not know the rate the TGID are scanned for each new channel grant or channel update I cannot tell how important the number of TGID will be for scan speed. You could reduce your TGID in half just to run a few benchmarks to see if it seems to make any difference.

Let us know if you find anything.
 

B-One

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Geeze! I've learned more about trunking in terms that I can understand on this thread than I have learned from all of the tech publications I've perused on the web. Thanks a ton lep and N0UDG.

So if I am understanding correctly, the scan speed is more dependent on the characteristics of the control channels that are programmed into the scanner than it is on the receiving radio itself.

K9jus, The number of sites is limited by the range you choose. I have gone further limit the number of sites by programming only the ones I can actually receive in my favorites lists. One can manually lock out sites one does not desire to scan as well.

To determine which sites I could receive with my setup, I accessed the "Site Information" menu from the face of the scanner by stopping pressing the "<" key on the right side of the display next to the Allied Radio Matrix for Emergency Response bar at the top. I then pressed on the "Advanced" key. Then I hit "Site Information." All of the sites for the entire state popped up. The orange and red ones were locked out by the range that was programmed into my profile. The black ones were the ones that the scanner was monitoring.

One can press on any of the sites to get more info, avoid the site, or see the site frequencies. Press the "Site Frequencies" button to display the frequencies. One can then press on any of the frequencies to listen in. I pressed on each frequency to find the control channel (The control channel sounds different than the others, once you find one you will know what I am talking about. One could also find the control channel published on RR). If there was no control channel apparent, I knew that the site was beyond the range of my setup. Once you find a control channel within range, information about that channel registers on the top of the display. You can also see the signal strength of the site at the top right of the display.

That was a bit lengthy, but I hope it helped you the way the others have helped me.
 

N0UDG

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Geeze! I've learned more about trunking in terms that I can understand on this thread than I have learned from all of the tech publications I've perused on the web. Thanks a ton lep and N0UDG.

So if I am understanding correctly, the scan speed is more dependent on the characteristics of the control channels that are programmed into the scanner than it is on the receiving radio itself.

K9jus, The number of sites is limited by the range you choose. I have gone further limit the number of sites by programming only the ones I can actually receive in my favorites lists. One can manually lock out sites one does not desire to scan as well.

To determine which sites I could receive with my setup, I accessed the "Site Information" menu from the face of the scanner by stopping pressing the "<" key on the right side of the display next to the Allied Radio Matrix for Emergency Response bar at the top. I then pressed on the "Advanced" key. Then I hit "Site Information." All of the sites for the entire state popped up. The orange and red ones were locked out by the range that was programmed into my profile. The black ones were the ones that the scanner was monitoring.

One can press on any of the sites to get more info, avoid the site, or see the site frequencies. Press the "Site Frequencies" button to display the frequencies. One can then press on any of the frequencies to listen in. I pressed on each frequency to find the control channel (The control channel sounds different than the others, once you find one you will know what I am talking about. One could also find the control channel published on RR). If there was no control channel apparent, I knew that the site was beyond the range of my setup. Once you find a control channel within range, information about that channel registers on the top of the display. You can also see the signal strength of the site at the top right of the display.

That was a bit lengthy, but I hope it helped you the way the others have helped me.
I too have used your method of listening to the control channel in different sites to see if I could pick them up. However, I found two sites in the summer that disappeared in the winter. I discovered that if I went to RR where you mention they list the control channels and click on the blue underlined name of the city the site's tower is located it will cause a map to pop up showing the coverage area of that site's tower. I was just outside of the two that disappeared so now I knew why I could no longer get them. However, one I wanted to get year round so I put up a beam antenna in my attic, pointed it in the correct direction and now I get it year round.
 

B-One

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I too have used your method of listening to the control channel in different sites to see if I could pick them up. However, I found two sites in the summer that disappeared in the winter. I discovered that if I went to RR where you mention they list the control channels and click on the blue underlined name of the city the site's tower is located it will cause a map to pop up showing the coverage area of that site's tower. I was just outside of the two that disappeared so now I knew why I could no longer get them. However, one I wanted to get year round so I put up a beam antenna in my attic, pointed it in the correct direction and now I get it year round.
I apparently have a similar issue in the winter here as well. Sites I picked up with my Scantenna in the attic dropped when it got cold, so I switched to a cell phone antenna I had mounted up there as well. That Scantenna is great for VHF and local 800Mhz but it's limitations on 800Mhz have really shown themselves this winter. I have some sites that I should be receiving, but I am not for some reason. I pick those sites up less than 100' from my house with a tri-band mag mount on the car, but I can't get them with the attic mounted cell antenna, nor the same mag mount near the house.

I have a beam on it's way as well as a high gain mag mount 3G-GSM router antenna. I am going to play with antennas and their locations when it gets warmer, We will see how they perform.
 
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