Scan priority
Posted: Sun Apr 04, 2021 12:02 am
There have been some requests to implement priority scanning, where some channels have priority, however there has also been some confusion about what is technically possible.
None of the supported radios have 2 receivers in them, so its not possible to monitor more than 1 frequency at the same time.
Hence if the scan has stopped on one channel, the radio can't monitor another 'priority' channel without the Rx stopping on the current channel for at least 100 milliseconds.
Hence in VFO Dual watch, it would not be possible to apply a priority channel without causing Rx breakup while the radio changes frequency to check the 'priority' channel.
IMO, having the Rx drop out for 100 milliseconds every second, would be quite annoying, and I would definietly not want this happening during scanning.
The other way however that Scan Priority could work, would be for 1 or more channels to be checked more often than the channels which were not marked as 'priority' channels.
In this case, the firmware would effectively maintain 2 lists of channels to scan. One list would contain the channels marked as priority, and the other list for non-priority channels.
This however is where things get complicated.
Imagine that channels 1,5 and 10 are priority, and channels 2,3,4,6,7,8 and 9 are non priority.
One method to prioritise the scanning of the priority channels is to scan channels like this
1,2,5,3,10,4,1,6,5,7,10,8,1,9,2,5 etc
However this works best when there are only a few priority channels e.g. just channel 1, as the scan would look like this
1,2,1,3,1,4,1,5 etc
However, if there are 5 priority scan channels, the degree of priority of those channels would deminish
The alternative stategy is to scan all priority channels, then scan 1 non-priority channel
e.g.
1,5,10,2,1,5,10,3,1,5,10,4 etc
However, whether any form of priority scanning is necessary is quite debatable, as the maximum scan speed is around 20 channels per second, an entire zone can be scanned in around 4 seconds, so only very short transmissions may be missed during scanning.
None of the supported radios have 2 receivers in them, so its not possible to monitor more than 1 frequency at the same time.
Hence if the scan has stopped on one channel, the radio can't monitor another 'priority' channel without the Rx stopping on the current channel for at least 100 milliseconds.
Hence in VFO Dual watch, it would not be possible to apply a priority channel without causing Rx breakup while the radio changes frequency to check the 'priority' channel.
IMO, having the Rx drop out for 100 milliseconds every second, would be quite annoying, and I would definietly not want this happening during scanning.
The other way however that Scan Priority could work, would be for 1 or more channels to be checked more often than the channels which were not marked as 'priority' channels.
In this case, the firmware would effectively maintain 2 lists of channels to scan. One list would contain the channels marked as priority, and the other list for non-priority channels.
This however is where things get complicated.
Imagine that channels 1,5 and 10 are priority, and channels 2,3,4,6,7,8 and 9 are non priority.
One method to prioritise the scanning of the priority channels is to scan channels like this
1,2,5,3,10,4,1,6,5,7,10,8,1,9,2,5 etc
However this works best when there are only a few priority channels e.g. just channel 1, as the scan would look like this
1,2,1,3,1,4,1,5 etc
However, if there are 5 priority scan channels, the degree of priority of those channels would deminish
The alternative stategy is to scan all priority channels, then scan 1 non-priority channel
e.g.
1,5,10,2,1,5,10,3,1,5,10,4 etc
However, whether any form of priority scanning is necessary is quite debatable, as the maximum scan speed is around 20 channels per second, an entire zone can be scanned in around 4 seconds, so only very short transmissions may be missed during scanning.