Transcript AMATEUR TELEVISION

AMATEUR TELEVISION
What is Fast Scan ATV?
Fast scan TV is the transmission of ‘real time’
TV pictures just like you see on your TV set
ATV allows visual QSOs so you can see your contact
ATV Bands and Frequencies
70cms typically 435 – 436.5 Mhz
Monochrome transmission if using
AM modulated carrier
Colour permissible if using Vestigial Side-band (VSB)
Colour and audio permissible when using
digital transmission techniques which are currently
under development by various suppliers
(based on DVB-T) standards
ATV Bands and Frequencies
The 23cms amateur band ranges from
1.240 to 1.325 GHz
ATV simplex 1240 – 1260Mhz
ATV repeater inputs typically are:
1248, 1249, 1255 and 1280Mhz
Repeater outputs range from 1308 – 1318Mhz
Full colour video and audio using either AM or FM
Modulation
Nationwide network of ATV repeaters
ATV Bands and Frequencies
The 13cms Amateur band ranges from
2.310Ghz to 2.450Ghz
2.322 to 2.355Ghz & 2.370 to 2.390GHz
ATV Simplex operation and ATV repeater inputs
Repeater outputs on 2.435, 2.440 and recently
Being allocated to 2.420Ghz
Full colour video and audio using either AM or FM
Modulation
Nationwide network of ATV repeaters
ATV Bands and Frequencies
The 10Ghz amateur band ranges from
10.000 to 10.500GHz
ATV Repeater outputs typically 10.065 & 10.240
ATV Repeater inputs 10.315, 10.340 & 10.425Ghz
ATV Simplex operation typically between
10.225 to 10.250, from 10.350 to 10.368
and 10.412 to 10.437
Full colour video and audio using either AM or FM
Modulation
Nationwide network of ATV repeaters
How much does it cost?
Tx and Rx
70cm – As little as £10
23cm – About £150
13cm – About £150
10Ghz – About £50
Video sources
Most people own a video
camera and they can be
utilised readily for ATV use.
When in camera mode, most
output a video & audio signal
on the AV output socket.
Their sensitive microphones
provide excellent audio from
anywhere in the shack
Video sources
Modern digital video cameras
often have video out for
viewing photos on your TV
set and provide a ready video
source for ATV use.
The memory cards can also
Be loaded with test-cards
made on a PC using MS paint
or Paint Shop Pro etc and
displayed using your digital
camera via the video output.
Video sources
CCTV cameras are available for
a very modest price, some as
low as £20 new for a colour
camera
They are ideal for permanent
installation into the shack and
many ‘budget’ cameras are
supplied with a wide angle
3.6mm lens which is ideal for
shack views
Video sources
Digital photo viewers allow
for cheap and easy testcard generation.
They are available from £29
and accept most types of
digital camera memory
cards.
Test-cards can be
downloaded from the
internet ready to use.
•DEMO
Video sources
A PC fitted with a video card with TV
out can provide a great video source.
Live video from your webcam,
photos, AVI video files etc.
Don’t throw out that old computer! A BBC,
Spectrum, or Amiga amongst others are great for
Test-cards…
Operating & ‘P’ reports
ATV calling and talkback frequency is:
144.750Mhz
ATV signal reports are given using the ‘P’
grade which ranges from 0 to 5
Example…
P0 – Trace of a picture barely visible
extreme noise and often unstable
P1 Picture visible but very noisy
Only larger objects can be seen
P2 More picture detail visible but noisy
with weak and unstable colour content
P3 Good picture detail with small items
visible, good colour but still noisy
P4 Very good picture with slight noise
visible
P5 Perfect picture with no noise
70cms
(435Mhz) Band
Equipment
70Cms
70cms ATV can be received using an
up-converter such as the Microwave Modules
or Fortop converters between your 70cm
antenna and television receiver
70Cms
Some TVs and video recorders also tune down well
below 430Mhz especially older models
Also, all analogue cable TV boxes
70cms
Suitability can be checked by using a
low power transmitter on 435Mhz
Tune the receiver to BBC1 and carefully
tune down lower
If you receive a blank picture stop transmitting.
If the TV displays static when not transmitting
and a blank screen when the transmitter is on
you should be able to receive ATV
• DEMO
70Cms
Transmitting ATV can be achieved by using a
ready built transmitter such as the MTV435
by Microwave Modules
These can often be found on Ebay for about £40
70Cms
Mini-kits in Australia currently produce a
transmitter kit for about £35
70cm Modulators
A quick and cost effective way to get onto
70cm ATV is by using a modulator
An old radio can be easily be modified
If done correctly, the radio can still be used
for standard voice operation
Example of a Simple modulator
E isC&D
the
modulated
supply
to
the
collector
of
Closing
the
switch
(SW1)
allows
the
radio
to
is the
+v are
supply
common
Points
A&B
theand
video
input
the
PA final
function
as transistor
normal
Modifications to a typical PA
Remove Collector Decoupling
Components
Isolate the collector of the final
transistor
Connect the Modulator
Completed Modification
23cm (1.2Ghz)
Band Equipment
Complete 23cm Transceiver
LCD Controller
Transmitter
&
Receiver
G6ALU 20W Power
Amplifier kit
‘Junk box’ antenna for 23cm
Parts Required:
The XYLs best flan dish
30cm diameter
‘Junk box’ antenna for 23cm
Parts Required:
A Plastic Conduit Box
‘Junk box’ antenna for 23cm
Parts Required:
Some 2.5mm diameter
copper wire
A short length of
RG213 or better
A plastic cable gland to suit coax
Strip a length of wire 48cms
long and bend 90º in centre
Bend again 90º as shown
And again to produce the double
quad as shown below
Each side of the quad
should measure 6cm
Drill a hole in the centre of the dish and conduit
box to fit the gland.
Strip 5mm on the end of the coax as shown and tin
the braid and centre core
Next, fit the conduit box
onto dish with the cable
gland entry at the rear of the
dish. Insert the coax
through the gland from the
rear.
Solder the element to the coax
with the centre bend of the
element to the centre and the
open ends to the braid. The
element should be 3cm from
the dish
Use a soldering iron to
heat the wire to melt
the box while pressing
down on the element to
fix into position
Use hot-melt glue gun to seal the connections
and then fit the lid to the conduit box…
VSWR should be < 1.3:1
Adjustment is made by adjusting the distance
of the quad element from the back plane
Gain is approximately
11 – 12dBi (8.5 – 9.5dBd)
23cm RX from the ‘Junk Box’
An old analogue satellite receiver can be used to
receive 23cm ATV. Simply connect the 23cm
antenna to the LNB input. If there is no
preamplifier in line, the DC LNB voltage must
be disabled first of use a DC blocking capacitor
in series with the coax centre conductor.
13cm (2.3Ghz)
Band Equipment
Complete 13cm Transceiver
LCD Controller
Transmitter
&
Receiver
Spectrian
30W Power Amplifier
A ‘Junk-box’ Antenna for 13cm
Bi-quad antennas are easy to build and make a very
simple and cost-effective antenna for local
working 13cm ATV and for receiving GB3GG
Construction
Cut a piece of copper clad
board 123mm x 123mm
Next cut a piece of ½ inch
copper pipe 50mm long
Cut a 2mm notch half way
down the pipe as shown and
file square
Drill a hole in the centre
of the board and use a
reamer to make exact
fit to the pipe
Insert the pipe through the
board so the notched end is
16mm as measured from the
copper side of the board
Solder the pipe to the board ensuring
a good electrical connection and
physical rigidity
Strip the earth wire from
2.5mm twin and earth
and cut a length to
244mm
This is the element
Each side should measure
30.5mm
Find half way point and fold
into a sharp 90º bend
Find half way point and bend
again as shown
Bend again to make a square
Bend both sides to produce the
quad shape as below
Ensure both sides
measure 30.5mm
outside diameter
Ensure symmetry
Solder the open ends of the element to the copper pipe as shown
The bend should sit inside the copper pipe notch but not touch the pipe.
The element should be 16mm from the copper board
Strip 30mm from coax
as shown
Fold back braid and strip
insulation flush with braid.
Cut centre conductor to
leave 5mm as shown
Insert the coax into the copper pipe
So the coax is flush with the bottom
Of the notch and solder the centre
conductor to the element as shown.
Ensure the centre is not shorted to
The braid
Crimp the cable to the rear as
shown. If a crimp tool is not
available then carefully solder
the braid to the pipe at the
front
Completed Bi-quad antenna
VSWR should be < 1.3:1
Adjustment is made by adjusting
the distance of the quad
element from the back plane
Gain is approximately
11 – 12dBi (8.5 – 9.5dBd)
Vertically Polarized
Horizontally
Polarized
3cm (10Ghz)
Band Equipment
Complete 3cm Transceiver
Gunn Diode Modulator
Gunn
Oscillator
LNB
Analogue Satellite Receiver
Gunn Oscillators
Gunn diode oscillators can be obtained for
about £5. They can often be found in ‘DualTec’ PIRs and other Doppler type detectors
Here are the connections of a typical
Doppler head.
There are usually 3 connections, 7v
(gunn diode), 0v and receive diode
Modules can be tested by
applying 7v between the
gunn diode and ground.
Using another module,
connect a 50uA meter
between the receive diode
and ground
Simple 10Ghz Modulator
The above circuit is a simple way to transmit 10Ghz
video using a Gunn oscillator. It is video only with
no audio provision for simplicity
10Ghz ATV bits – Where to buy
Bob Platts G8OZP 01283-813392
Gunn Diode Modulator Boards
Modified LNB's
Receiver Kits
24cm Pre-amps
George Lewczenko G6AKC
01366-728773
Gunn Diode TX Modules
S. Marshall G6NHG
01827-8979202
20db Horns & Slotted
Waveguide Antennas
23cm Where to buy
Tonna 23cm Antennas (Waters and Stanton)
20636 Tonna 23cm (ATV) (1240 - 1260MHz) 35 el Yagi £64.95
20650 Tonna 23cm (ATV) (1240 - 1260MHz) 55 el Yagi £84.95
Comtech Modules & ATV Controller www.13cm.co.uk
23cm PA Kit Steve Drury G6ALU
23cm Preamp kits
23cm Preamp (ready built)
www.radio-kits.co.uk
www.mini-kits.com.au
Bob Platts G8OZP 01283-813392
13cm Where to buy
Waters and Stanton
20745 Tonna 13cm (2300 - 2400MHz) 25 el Yagi
£69.95
Comtech Modules & ATV Controller www.13cm.co.uk
Spectrian Power Amplifier
Ebay Seller ID: Pyrojoseph
Search for:
“30W Class A Linear RF amplifier 2.3-2.45 GHz 2304 ATV”