Thread: 4NEC2?
View Single Post
  #33   Report Post  
Old October 14th 18, 06:39 PM posted to,
Ralph Mowery Ralph Mowery is offline
external usenet poster
First recorded activity by RadioBanter: Jul 2006
Posts: 662
Default 4NEC2?

In article ,
What STC actually asked was which sideband he should use for RTTY on

Which is, of course, an interesting question as it's not something
that was covered in any exam, current or previous.

My $0.02 worth is that it doesn't matter, since an RTTY operator will
know that he needs to invert the received tones if he sees a string
of "46464646" instead of "RYRYRYRY"

Here's what was asked, and it wasn't posted no archive, or deleted, or
any of the other weak bull**** that Burt has bean spraying around:

"Was pottering at my radio last night, heard the scream of data being sent
and was triggered to revisit a long parked project; getting going on RTTY!

Here's the hardware I'm using:

Yaesu FT757-GXii Serial/USB cable interface thing PowerMac G4 running

I've got everything hooked up, have CocoaModem configured and displaying a
waterfall but when set to RTTY mode it's just decoding gibberish...

Other than a couple of short spells at club days, this is my first go at
this and I have no idea what I'm doing... Any tips?"!or...A/_ityI76x0IMJ

Good old Burt.

If the wrong sideband or inversion of the tones is the problem, it will
not be a string of 4646 instead of RYRY. They are both the same except
the printer is shifted for the 4646. What will hapen is that instead of
RYRY it will be YRYR but all the other characters will be scrambled.

It does not matter what sideband is used for RTTY if the tones are
inverted. However in most normal ham RTTY lower side band is used for
receiving and if audio tones are fed into the audio for transmitting.
This makes the tones come out the same when used on AM or FM on VHF.

For HF it does not even matter what the frequency of the audio tones are
if they are the usual 170 Hz difference as long as they pass through the
audio of the transmitter and receiver. Usually 2125 and 2295 are used
as this is about as high as will pass the audio and if running a ssb
transmitter the 2 nd and higher harmonics are filtered out to some
extent if need be by the transmitter filter.