NARROW BAND FREQUENCIES

[scannerman200]

If you put in a narrow band frequency in a conventional scanner, it will automatically change it to a different frequency. Can the frequency still be heard once put in scanner as it would be heard in a narrowband scanner?

 

[DaveH]

There are a couple of problems. If the frequencies are on steps that your scanner doesn't support, the scanner will round to the closest one. It will sound off-frequency, and there is nothing to do about it. The other thing is that a narrowband channel will have lower audio than a "regular" one. Sometimes I crank the volume to the end, and depending on the radio, it is barely enough, and the squelch tail is still very loud.

I wonder how trunktracking scanners will behave, but have not tested this. Suppose an LTR system uses (say) 453.11875 (6.25kHz steps) and you can only program 12.5kHz steps (452.1125 or 453.1250). It would be off by 6.25kHz, which would probably screw up the decoding.

Dave

 

[loumaag]

Well, I cannot comment about LTR decoding, but I will tell you that the Pro-96 rounds and since the passband for FM is some 18KHz wide, it makes no differnce. Here we have a statewide VHF TRS. One of the local towers (13) occasionally uses 157.3125 as a CC. The Pro-96 has this as 157.3150 and it has no problem handling it as a CC. I will grant you that a SNFM channel does have lesser deviation and hence the volumn will seem lower, but as far as the rounding goes, don't worry about it too much.