Feature Articles

Getting Started

With digital modes you can work other amateur radio stations throughout the world with transmitter powers of 10 Watts or less using simple wire antennas.

WSPR map snapshot - 40m activity 23rd Feb 2016

You need an HF transceiver, antenna, computer and interface unit with suitable cables and software for your chosen mode(s). If you have a transceiver with a computer control interface, you may be able to connect it to the computer so that you can read and control the frequency directly. The interface unit serves to match the signal levels of the audio and isolate the Push to Talk (PTT) connection between the radio and the computer. If the transceiver has the Voice-Operated Switch (VOX) feature you may be able to use this instead of the PTT in which case you only need to connect the transmit and receive audio to the computer.

 

Digital Modes RTTY and PSK31

The digital modes RTTY and PSK31 are the easiest to begin with and enable you to have a QSO in plain language at a reasonable speed. RTTY has no error correction but PSK31 does, and can provide a good error free readout providing the signal is slightly above the noise level. For RTTY, start with the MMTTY software and check the AA5AU website which provides a lot of information on setting up the software. For PSK31 you can try MMVARI or DIGIPAN software.

The Fldigi software by W1HKJ incorporates RTTY, PSK31 and many other digital modes (except for the WSJT weak signal modes) and enables you to switch between modes quickly.

This software is installed on the MSARS computer in the radio shack.

 

Weak Signal Modes – WSJT, WSJT-X and WSPR

WSJT, WSJT-X and WSPR developed by Joe Taylor K1JT, are programs designed for weak-signal digital communications.

WSJT has digital protocols (JTMS, FSK441, ISCAT, JT6M, JT65 and JT4) optimized for Earth-Moon-Earth, Meteor Scatter, Ionospheric Scatter at VHF and UHF and also HF Skywave Propagation.

WSJT-X implements a new protocol JT9 optimized for the LF, MF and HF bands.

WSPR (Weak Signal Propagation Reporter) is designed for sending and receiving low power MF and HF signals to test propagation paths. WSPR Version 2.11 also includes a package ‘FMT’ which enables you to make accurate frequency measurements such as those used by participants in the ARRL Frequency Measuring Tests ‘Challenge’.

JT65-HF is a development of the WSJT program specifically for HF by Joe Large W6CQZ.

You need to use software such as ‘Dimension 4’ to synchronise your computer with an accurate clock so that the software decodes the messages accurately.

For most of these modes you are able to exchange signal report and callsign, not really a conversation by any means, but still a contact!

 

More Digital Modes

There are even more digital modes to try such as Olivia and FSQ once you have conquered the simpler modes if you want a challenge. There is also a software implementation of the HF digital voice algorithm called ‘FreeDV’. However, try the simpler modes first as they are more popular and you will find more stations on the air using them before experimenting with other more complex modes.

 

Sources and Suppliers

Radio to Computer Hardware Interface

ZLP Electronics: www.g4zlp.co.uk

Tigertronics SignaLink: www.tigertronics.com

G3LIV: www.g3liv.co.uk

Radioarena: radioarena.co.uk

WM2U: www.qsl.net/wm2u/interface.html

Signalink USB front panelTigertronics Signalink USB

 

Digital Mode Application Software

MMTTY and MMVARI: hamsoft.ca

DIGIPAN: www.digipan.net

FLDIGI: www.w1hkj.com

WSJT WSJT-X and WSPR: physics.princeton.edu/pulsar/K1JT/index.html

JT65-HF: sourceforge.net/projects/jt65-hf

Olivia: www.oliviamode.com/index.htm

FSQ by ZL1BPU: www.qsl.net/zl1bpu/MFSK/FSQweb.htm

 

PC Clock Synchronisation Software

Dimension 4: www.thinkman.com/dimension4

UK National Physics Laboratory: www.npl.co.uk/science-technology/time-frequency/products-and-services/time/time-synchronisation-of-computers-to-utc(npl)

Meinberg NTP: www.meinbergglobal.com/english/sw/ntp.htm

 

Information

AA5AU Getting Started on RTTY: www.aa5au.com/rtty/getting-started-on-rtty

British Amateur Radio Teledata Group (BARTG): www.bartg.co.uk

ARRL: www.arrl.org/digital-data-modes

G4UCJ: hfradio.org.uk/html/digital_modes.html

WB8NUT: wb8nut.com/digital

Essex Ham: www.essexham.co.uk/how-to-get-started-with-data-modes

RTTY.COM: www.rtty.com/index.htm

 

Band plans and frequencies

RSGB: rsgb.org/main/operating/band-plans

HFLINK: https://hflink.com/bandplans

 

YouTube

K7AGE PSK31 videos: www.youtube.com/playlist?list=PL8D7C6EBD6E2081E2

 

Further reading

RTTY/PSK31 for Radio Amateurs By Roger Cooke G3LDI

Get on the Air with HF Digital By Steve Ford WB8IMY

Work the World with JT65 and JT9 by Steve Ford WB8IMY

 

An introduction to Fox Hunting particularly for MSARS members.

Below are the instructions of a typical MSARS Fox Hunt (Please Note may well vary from Hunt to Hunt.)

As usual the start time from Cyprus Road car park will be at 7.30pm. First transmission from the Fox will be at 7.30pm. Thereafter each transmission will be every 15 minutes, i.e. 7.45, 8pm, 8.15pm, 8.30pm etc. Each transmission will be for a duration of 2 minutes.

Arrive at the car park in plenty of time to allow you to set up and be ready for the first transmission.

At the start you will have been given a sealed envelope which contains the name of the pub near to where the foxes lair is. On no account should the envelope be opened, unless you have been unable to find the fox and given up. In this case open the envelope, and you will find details of the name of the pub and where it is located.

For the hounds that have found the foxes lair, please hand in your sealed envelope to Mr Fox.

The transmissions will be on a frequency of 145.400MHz. If this frequency is in use, you will be given an alternative frequency.

Map, Compass, Ruler and pencil are useful when taking various bearings of Mr Fox’s transmissions. In most cases Ordnance Survey Map 198 will suffice.

Clues will be transmitted by the Fox at 8.45pm, 9pm, and 9.15pm.

You will of course, need a device that will receive the transmissions. This could be a portable VHF receiver or transceiver. The antenna could be a simple whip using your body to act as a reflector/shield. Alternatively, a more sophisticated directional antenna such as a HB9CV antenna could be employed.

Many different types of antenna have been used over the years, and some of the most primitive of antenna have helped in successfully finding the Fox.

As you get closer to the Fox the signal from him will generally get stronger, and direction finding might become a problem as his signal will be reflected off buildings and the like. This is where an Attenuator is very useful. A few of the club members have made these in the past. This would make a good club project for the new members.

Each car and its occupants will be treated as one hound. A friend is welcome to accompany a member providing they travel in the same vehicle.

Please note that the actual start time of a Fox Hunt, the duration of transmissions and the chosen frequency from the Fox may vary.

Full details of any particular hunt should be shown on the events page of this website.

Enjoy - Its great fun!

Tony G3XQM

HF Propagation Predictions - February 2016

Courtesy Chris G3YTU

Download as a .pdf file

Reduction of RFI for the Mobile User

Courtesy Phil M5BTB

Download as a .pdf file

Decibel to Power Conversion Chart for the Radio Amateur

dBW Watts   Watts dBW
         
0 1.0      
1 1.3   1  0.0
2 1.6   2  3.0
3 2.0   3  4.8
4 2.5   4  6.0
5 3.2   5  7.0
6 4.0   10  10.0
7 5.0   15  11.8
8 6.3   20  13.0
9 7.9   30  14.8
10 10.0   40  16
11 12.6   50  17.0
12 15.8   60  17.8
13 20   70  18.5
14 25.1   80  19.0
15 31.6   90  19.5
16 39.8   100  20.0
17 50.1   120  20.8
18 63.1   140  21.5
19 79.4   160  22.0
20 100   180  22.6
21 125.9   200  23.0
22 158.5   240  23.8
23 199.5   280  24.5
24 251.2   320  25.1
25 316.2   360  25.6
26 398.1   400  26.0