SSB and CW

[crazy_19]

I can pick out W1AW's morse code bulletins with my radio in USB so why do some radios have modes called CW??

 

[ka3jjz]

Some radios adjust the pitch and tone, and on occasion, the bandwidth, of the received signal when modes such as CW are switched in. Mostly ham gear, but I've seen it on other radios, too (Some Drake radios had a dedicated RTTY mode, as did JRC radios, for example)

Mike

 

[ko6jw_2]

It's a question of bandwidth. For sideband my radios have 2.4kHz Collins filters. For CW they have 500Hz Collins filters. You can receive CW in the USB position, but in crowded band conditions the narrower filters are needed. Some operators use 300Hz CW filters. The narrower the bandwidth the better the S/N ratio.

 

[Boombox]

With ham rigs and the higher end SW tabletop radios, it's a matter of filtering, like KO6JW said.

With CW you still use an SSB product detector to decode the signals (or a BFO on cheaper radios), but if you are into CW you generally are going to use a much narrower filter than you will for SSB.

With some SW radios, it's just labelled for convenience.

The FRG-7 and DX-394 are examples of SW radios with a CW marking on them for convenience (I'm using those as examples because I am familiar with those radios). When you switch to CW on such radios you're just switching on the BFO or SSB product detector (BFO for the FRG-7, USB or LSB with a narrower audio filter for the DX-394).

 

[krokus]

I can pick out W1AW's morse code bulletins with my radio in USB so why do some radios have modes called CW??

For ham rigs, in addition tobfiltering people have mentioned, there is the transmit portion, too. In SSB, there should be signal output be just keying the radio. In CW mode, the radio transmits at whatever power level it is set for.

Sent via Tapatalk