[Lowfer] Mark - Space Frequencies / Frequency Spread((3)

[Clive S Carver]

Hi Frank

In part answer to your (1) 518 kHz represents the centre frequency, thus
518.085 kHz and 517.915 kHz. This from professional experience.

Now, according to my Klingenfuss Radioteletype Code Manual Edition 13

Data Level 0 = higher frequency = space = B (on a radio circuit) = Start

Whereas

Data Level 1 = lower frequency = mark = Y (on a radio circuit) = Stop

I retired from the merchant navy before 490 kHz came into use, but I would
be absolutely amazed if any different to the above.

(2) I recognise those frequencies as being the centre (or assigned
frequency) basically either ending in .0 or .5 kHz. The link you give has
the note beginning "Assigned frequencies shown, for carrier frequencies
subtract 1.7 kHz." Professionally I used receivers where on selecting F1 as
the mode, the dial frequency was the centre/assigned frequency and I also
used receivers where this was not the case and it was necessary to subtract
a frequency, typically 1.5 kHz or 1.7 kHz from the "book" frequency. (I
sailed on one ship where the modem had been set to 1.0 kHz to make the
arithmetic easier, ie just subtract 1.0 kHz) this with the receiver
effectively in USB mode.

(3) I have no knowledge on WSPR and JT-9

Re (1) and (2)  NAVTEX and SITOR-B use the same FEC system, just that a
NAVTEX receiver can select stations. On ships where there was no dedicated
NAVTEX receiver (in general if there was a NAVTEX receiver there was no need
for me to be there!) I could and did receive wanted NAVTEX transmissions
using the SITOR-B/FEC Modem.

73's

Clive

GW4EYO


-----Original Message-----
From: Lowfer [mailto:lowfer-bounces at mailman.qth.net] On Behalf Of Frank
Lotito
Sent: 23 April 2015 19:19
To: 600 / 630 Meter Group; Lowfer Bulletin Board
Subject: [Lowfer] Mark - Space Frequencies / Frequency Spread((3)

Can one or more members refer me to authoritative sources detailing or
discussing the following information:
(1) For 490 and 518 KHz Navtex, what are the actual transmitted "mark" and
"space" frequencies? (Of course, the difference of these two frequencies is
170 Hz.)
(2) For HF Sitor-B transmissions cited by NOAA, what are the transmitted
mark and space frequencies? For example, the US frequencies cited on the
following URL http://www.nws.noaa.gov/om/marine/hfsitor.htm
(3) For 630 meter experimental stations, what are the upper and lower
frequencies of the sub-band commonly used for WSPR and JT-9 transmissions?
I am not interested in what frequencies you specifically "dial in" on your
receiver / transceiver system.  
73 Frank K3DZ / WH2XHA