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| To: | "[email protected]" <[email protected]> |
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| Subject: | Re: LF: SDR programs |
| From: | M0FMT <[email protected]> |
| Date: | Tue, 26 Jun 2012 01:08:18 +0100 (BST) |
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Hi Graham OK a subtle point AM is a "Transparent" mode FM is a "Capture" mode and as such not suitable for AC use where simultaneous transmission can block calls. Small random offsets in carrier frequency cause hetrodynes that alert ATC of the presents of a weaker call. Nothing in Marine is ever that immediate so I guess it was expedient to opt for the El-Cheapo FM solution there can be no other reason. Probably a bunch of Civil Servants were conned into believing AM stood for Ancient Modulation. You are right there are lot of extras that could be added to SDR software and perfectly feasible we just need to learn to programme and add all the goodies we think are needed or find a friendly software jockey to do it for us...... hee! As far as up converters go the ubiquitous chip is the multiplex FST3253 used in Softrock and other well known up-converters for RX and TX switched with a 90 degree phase shift LO from a pair of 7474 flip flops is the basis for most current SDR detectors or TX mixers. There are now relatively cheap A/D converters which give a wider BW than the are currently available Sound Card solution. And now its all being integrated onto a single IC so your comment earlier about a USB stick TX is with us. It just needs a mass market for the price to come right down and I guess it comes through the Mobile Phone
market. Big bang doesn't frighten me all bottles here matey retro shack thermionic not thermonuclear. You'll be telling me next that the Moons gravity bends light ergo radio waves? It's late!!! 73 es GL Pete M0FMT IO91UX From: Graham <[email protected]> To: [email protected] Sent: Monday, 25 June 2012, 23:38 Subject: Re: LF: SDR programs R Pete
Ahh By split , I mean the anti-jam
in channel split , When on the same frequency,
the ground TX (used tobe ?) off set
from the aircraft Tx frequency , so if
the Aircraft TX jammed 'ON' then other aircraft
could still receive the ground , that
was the reason for wide IF pass bands
and keeping to AM for the comm.'s ....
Marine coms , adopted FM ...
There is a afc for cw
OT ? over the top more like , the disclaimer
on the yab-a-dab-a-doo group is bigger than
the space left for the messages , I think the
name Black-Sheep seems to be quite apt
now !,
Big-bang , according to my arrl hand
book , HF communications will tend to be
attenuated in the direction of the burst ,
assume by producing quite a big
Fariday screen , also recommends you keep
your radio in a metal sweet tin ala blue
peter garden !
Did get good signals on the MW on the
way to work from France during the
eclipse some time ago , due to the lack of
ionisation
G..
Hi Graham
............ to monitor off frequency nets and the tower/aircraft
split............... ? there is no split frequency working the Tower and
A/C both use the same QRG its just that the A/C being at altitude can
be heard the Tower being low and beyond your radio horizon can not be
heard........ if thats what you ment.
I use the say (A) LO for Approach and then say (B) LO for Tower
so when the hand over from Approach to Tower occures I merely click the
appropriate LO A or B. Usually a 3 to 4 meg shift, well it is at Luton AP
anyway.
Sorry wrong end of the spectrum for this reflector........ just as
well the RSGB attention is with the Yahoo mess otherwise we may be getting our
keying fingers rapped!!!!!!
73 es GL Pete M0FMT IO91UX
From: Graham
<[email protected]> To: [email protected] Sent: Monday, 25 June 2012, 21:19 Subject: Re: LF: SDR programs Yes I think Andy gave a talk at the egham
convention on using a/d from mobile phones ,
the new ones had the extra bits to give
the full dynamic range on HF ..he was
using hardware block convertors ......... never
saw any items offered for sale
........only some very high price 'HF rx'
using the same ideas ...I think the
give away is the band being covered in
frequency blocks , which I assume is down to
the down convertors
Dont think he is monitoring BS now , or
we might of got the fill in, but one
things is certain, the £10 , wonder-dongle has
saved me from buying a R7000 ...All we
need now is a little more stability in
the control software and a
wide-band FM option in HDSDR
Im getting the gb3ang beacon on 70 Mhz
good signal with my indoor 2 ele quad
.......... the PMR band on 446 Mhz with the
co-linera from 10 miles away in liverpool ssb on 144 MHz
etc
Definable FM-AFC (AND AM)
would be handy to monitor off
frequency nets and the tower/aircraft split
I think possible the driver software
could improve as more take up the
idea ....... could HDSDR have its own driver
code block .......... Ive noticed there is a
routine that some times appears that
'purges' the device ......now if that could
be run at will , that would be a big
help, to recover a locked system
73 -G.
Hi Bob
If you are directing that mail to me then you need to look at earlier
posts.
However if you are a cheque book Ham then it will be of little
interest to you.
You say dangle we say dongle..... :-0
These are TV front ends that use the SDR principle and plug straight
into your USB port on your Lap top. Normally they are for recieving local
digital TV and radio plus a FM band as well. They are available in the US and
they can be made to tune from about 60megs to about 1.7gigs. If I need to
tell you more please ask but this is all in public domain on the web (but not in
Ham mags, at least not in UK). I have played with these things for about 6
months now and for a few quid (dollars) are fun. If you build a simple up
converter with a say a 60meg LO guess what, you have an all band HF radio
as well.
Oh and BTW I was not entirely sure what Tracy was getting at below??
We are talking 10 dollars not 300+dollars.
73 es GL Pete M0FMT IO91UX
From:
"[email protected]" <[email protected]> To: [email protected] Sent: Monday, 25 June 2012, 19:34 Subject: Re: LF: SDR programs
Been Kinda out of any loop on this
BUT
if what I read,, if I connect a TV tuner usb dangle witht he correct chip
set
it will cover MF to HF using an appropriate program. I use HDSDR with
my SDR IQ
which I like for general reception. So by using the proper chip set
HDSDR
will run that TV dangle as a HF radio
??
Bob K3DJC
On Thu, 21 Jun 2012 22:31:00 +0100 "Tracey Gardner" <[email protected]>
writes:
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