Re: [digitalradio] RTTY and mode selection on radios
RTTY "should" be used in the LSB mode regardless of the band. I don't use software for RTTY so I cant tell you a thing about that.
Re: [digitalradio] RTTY and mode selection on radios
--- On Fri, 2/19/10, James French wrote: > From: James French > Subject: [digitalradio] RTTY and mode selection on radios > To: digitalradio@yahoogroups.com > Date: Friday, February 19, 2010, 3:58 PM > Wondering if someone can point me to > a link or some literature explaining > about why there is a FSK mode on the HF radios like the > Icom ic-746pro, > Kenwood TS0940sat, and Ten-tec Paragon (585)? Is there a > reason for this? > > I am asking this because I have listened to some RTTY using > either USB or LSB > dependent on what band I am on and could copy it with any > software programs I > have but then switched to the FSKmode on the radios and > loose the signal > completely. > > Is this mode just for the older ancient RTTY eqiupment to > interface with the > radio? > > I haven't tried to send any RTTY yet but planning to be on > the air next > weekend for the NAQP RTTY contest from the Red Cross > station in Ann Arbor,MI. > > > James W8ISS > > RTTY should not be referred to as afsk even if audio is fed into a ssb radio. What comes out of the transmitter is the same if true FSK or AFSK is used. Whoever started that wording should be shot. It is AFSK if AM or FM is used. For the ham bands rtty should be received and transmitted in the LSB mode on all bands if ssb is used.YOu can set the tones up in reverse and use usb, but it is not recommended. When you switch from lsb to the rtty mode, most receivers will shift up or down 2125 hz if you have it set up correctly. That is what the mark tone should be. Actually any two tones can be fed into a ssb transmitter as long as they are 170 hz apart. The lowest tone should be around 1500 hz or so as the second harmonic of it will be out of the pass band of the filter. The station on the other end will not know the differance, just your dial frequency will not match his. RTTY was origionally sent on the low bands by shifting the frequency of the transmitter lower in frequency when the space was sent. When ssb transceivers came into use it was found that if you put a pure sine wave into the microphone input you generated just a single output frequency. If that audio tone was changed a small ammout the frequency of the output would change the same ammount. If usb is used the frequency would shift up and if lsb was used the frequency would shift down. LSB is used to keep everything the same weather the shift was the actual carrier or if audio tones are used. You have to have a good understanding of how a single frequency fed into a ssb transceiver will change the output frequency to understand rtty.
Re: [digitalradio] RTTY and mode selection on radios
FSK is RTTY but so is AFSK. Some rigs support the use of RTTY in FSK while others require a TNC or sound card to generate the tones. FSK on transceivers tends to invoke narrower filters and the frequency you are receiving is displayed differently. The serious RTTY guys tend to prefer FSK. This post from the N1MM Logger reflector illusrates some issues.. (see also http://www.mcwa.org/AFSKvsFSK.pdf) Doug Haft wrote: > > Are you running AFSK, or FSK? Does this mismatch in frequency happen on > every spot, or randomly? If AFSK, which sideband, LSB or USB? I haven't > thought this trough, so I might be off base here, but its possible the > spotter is running AFSK. So, their rig is in USB (or LSB). Their audio > tones will be up (or down if using LSB) in the sideband. The freq on their > rig will be offset from where the "tones" really are. If you're running > FSK, you'll tune to the freq they spotted, but the target station won't be > there! Worse yet, if you're in USB running AFSK and the spotting > station is > in LSB AFSK... the spot he puts out will be quite a ways from where > you land > as a result of clicking that spot. > > > On Fri, Feb 19, 2010 at 3:58 PM, James French wrote: > > > Wondering if someone can point me to a link or some literature explaining > about why there is a FSK mode on the HF radios like the Icom ic-746pro, > Kenwood TS0940sat, and Ten-tec Paragon (585)? Is there a reason for this? > > I am asking this because I have listened to some RTTY using either USB or > LSB > dependent on what band I am on and could copy it with any software programs > I > have but then switched to the FSKmode on the radios and loose the signal > completely. > > Is this mode just for the older ancient RTTY eqiupment to interface with > the > radio? > > I haven't tried to send any RTTY yet but planning to be on the air next > weekend for the NAQP RTTY contest from the Red Cross station in Ann > Arbor,MI. > > James W8ISS > >
[digitalradio] RTTY and mode selection on radios
Wondering if someone can point me to a link or some literature explaining about why there is a FSK mode on the HF radios like the Icom ic-746pro, Kenwood TS0940sat, and Ten-tec Paragon (585)? Is there a reason for this? I am asking this because I have listened to some RTTY using either USB or LSB dependent on what band I am on and could copy it with any software programs I have but then switched to the FSKmode on the radios and loose the signal completely. Is this mode just for the older ancient RTTY eqiupment to interface with the radio? I haven't tried to send any RTTY yet but planning to be on the air next weekend for the NAQP RTTY contest from the Red Cross station in Ann Arbor,MI. James W8ISS
