BCD436HP/BCD536HP: Auto modulation performance?
- Thread starter runnerr
- Start date
JvdK
Member
It is always better to use the correct modulation if you know it. Everytime the scanner finds a transmission he has to determine the modulation. For one hit it might not take long however with more frequency hits this time will ad up.
Either way works. I attend military airshows. Some of the military air frequencies use FM so I might pick FM instead of Auto. But I usually leave it on Auto as they might change from one year to the next, both frequency and/or mode. (Sometimes I may have picked the wrong mode but can’t tell the difference due to my close proximity to the aircraft. And sometimes I can discern I’ve picked the wrong mode and change it.) When set to Auto I haven’t noticed the scanner picking the wrong mode, so I’d say they got it right when they offered the Auto feature in the newer scanners. And, you can play with the settings yourself and your results will dictate what you choose.
Not sure where your located but you have a 436 which will pull from the database so anything air related will pull in the correct setting. That is if your data is listed in the database. Some mil use Fm and also P25.
Ubbe
Member
It takes the auto setting from the bandplan that have been programmed.
When you scan or search ranges it only goes by if it detects a carrier that the squelch has indicated. Then it stops scan or search and look to the SD card what has been programmed for the modulation type and if set to auto it looks in the bandplan what have been set and use that value to configure the DSP, and then continue to check what CTCSS/DCS or NAC/RAN/ColorCode that can be detected.
That extra procedure to look in the bandplan doesn't add anything to the scan or search rate, it's less than a millisecond as the data are in the scanners own work memory, and it only does it when it has already stopped on a frequency.
/Ubbe
When you scan or search ranges it only goes by if it detects a carrier that the squelch has indicated. Then it stops scan or search and look to the SD card what has been programmed for the modulation type and if set to auto it looks in the bandplan what have been set and use that value to configure the DSP, and then continue to check what CTCSS/DCS or NAC/RAN/ColorCode that can be detected.
That extra procedure to look in the bandplan doesn't add anything to the scan or search rate, it's less than a millisecond as the data are in the scanners own work memory, and it only does it when it has already stopped on a frequency.
/Ubbe
But what happens if the modulation set in the bandplan is the wrong one for the current transmission for i.e. FM instead of AM? How do it knows that?
Thanks for your help!
(Hej from Sweden!)
Ubbe
Member
It doesn't know it's wrong, it just uses what is in the bandplan if you have set the mode to auto. So it will use FM for VHF AIR if you have set that in its bandplan and will sound terrible.
/Ubbe
