FT-8 New digital mode 8-FSK modulation

It’s still in beta testing, but FT8 — the latest digital bauble to capture the imagination of the Amateur Radio community — has been luring away many of those already using the popular JT65 “weak-signal” mode. FT8 is included in a beta release of WSJT-X, version 1.8.0-rc1. Among its biggest advantages is a shorter transmit-receive cycle, meaning quicker contacts. The notes for the “candidate” release say that FT8 offers “sensitivity down to –20 dB on the AWGN channel.” Contacts are four times faster than with JT65 or JT9, and an entire FT8 contact can take place in about 1 minute.

The new mode is named after its developers, Steven Franke, K9AN, and Joe Taylor, K1JT. The numeral designates the mode’s 8-frequency shift keying format. Tones are spaced at 6.25 Hz, and an FT8 signal occupies just 50 Hz. Unlike JT65 or JT9, transmit and receive cycles in FT8 each last about 15 seconds. Like JT65, FT8 requires accurate time synchronization. An auto-sequencing feature offers the option to respond automatically to the first decoded reply to your CQ.

“FT8 is an excellent mode for HF DXing and for situations like multi-hop Es on 6 meters, where deep QSB may make fast and reliable completion of QSOs desirable,” Taylor’s release notes assert.

The beta release came out just days before the July CQ VHF Contest and proved to be a boon to many operators who took advantage of FT8 on 6 meters. In a limited outing for the CQ VHF, Frank Donovan, W3LPL, made 22 FT8 contacts on 6 meters, “during which the FT8 software reported SNRs from my receiver below –10 dB (measured in a 2,500-Hz bandwidth). Some of the 22 QSOs may have been difficult to complete on CW.”

Enthusiasts will have to wait a little longer for Logbook of The World (LoTW) to accept FT8 contacts as FT8 contacts. Because FT8 is still in beta, it has not yet been added to the ADIF tables. Configuring TQSL to automatically map FT8 contacts to “DATA” will enable users to upload FT8 contacts now, and confirmations will be valid for DXCC Digital, VUCC, WAS Digital, and WPX Digital awards. A new TQSL configuration will be released once the new mode has been accepted to ADIF, which could happen within a week.

Important characteristics of FT8:

– T/R sequence length: 15 s
– Message length: 75 bits + 12-bit CRC
– FEC code: LDPC(174,87)
– Modulation: 8-FSK, keying rate = tone spacing = 5.86 Hz
– Waveform: Continuous phase, constant envelope
– Occupied bandwidth: 47 Hz
– Synchronization: three 7×7 Costas arrays (start, middle, end of Tx)
– Transmission duration: 79*2048/12000 = 13.48 s
– Decoding threshold: -20 dB (perhaps -24 dB with AP decoding, TBD)
– Operational behavior: similar to HF usage of JT9, JT65
– Multi-decoder: finds and decodes all FT8 signals in passband
– Auto-sequencing after manual start of QSO

*Comparison with slow modes JT9, JT65, QRA64:* FT8 is a few dB less
sensitive but allows completion of QSOs four times faster. Bandwidth is
greater than JT9, but about 1/4 of JT65A and less than 1/2 QRA64.

*Comparison with fast modes JT9E-H:* FT8 is significantly more
sensitive, has much smaller bandwidth, uses the vertical waterfall, and
offers multi-decoding over the full displayed passband.

*Still to come, not yet implemented:* We plan to implement signal
subtraction, two-pass decoding, and use of “a priori” (already known)
information as it accumulates during a QSO.

Three extra bits are available in the message payload, with uses yet to
be defined. We have in mind special message formats that might be used
in contests, and the like. Your considered suggestions for use of these
bits are very welcome!

K1JT, K9AN, and G4WJS have conducted on-the-air tests of FT8 with
excellent results. We’re now at a stage where tests under a wider range
of conditions are desirable. If you can build WSJT-X from source code
revision r7750 or later, and would like to help, please do so and report
your results to us! Pre-built installation packages will be made
available after further testing is completed.


FT-8 New digital mode 8-FSK modulation

Paul Leicester | MØFOX | Chesterfield UK | IO93HE | Icom IC-7300

SharkRF openSPOT DMR/FUSION/D-STAR hotspot

openspot01
openSPOT is a standalone digital radio IP gateway / hotspot

Supports DMR (Brandmeister, DMRplus), D-Star (DCS, REF/DPlus, XRF/DExtra, XLX), System Fusion (FCS, YSFReflector) networks. More supported networks and features will be available with new firmware releases.

Supports cross modem modes. Talk with your C4FM radio on DMR, and with your DMR radio on System Fusion networks!
Very easy to use, works without a computer. No additional hardware required, works out of the box. All accessories included.
Web interface for configuration and monitoring.
HTTP, UDP/TCP API support.
Custom 2FSK/4FSK RF protocol support with TDMA.

USB powered, low energy consumption, 20mW RF output.
Create your own private radio network using our open source server application.
Runs fully embedded software written in pure C, running on an embedded real time operating system. No Linux, bulky Windows software or failing SD cards!

Paul Leicester | MØFOX | Chesterfield UK | IO93HE | Icom IC-7300

DMR UK Core talk groups

REVISED TALK GROUPS
There will be several changes to talk groups affecting

TG8, TG2350, TG2351, TG2352, TG2353, UK Wide & Direct Dial
As of the 28th December 2015 the new Talkgroup structure has now been implemented. However the new regional groups will not be linked to TG8

This is to allow users time to update their code plugs and test them on the new talk groups

Talk groups TG8, TG2350, TG2351, TG2352, TG2353 & Direct Dial
are still available, but will be switched off on 31st January 2016
AS A GUIDE THE REVISED TALKGROUP LISTINGS SHOWN BELOW ARE NOW CONFIRMED AS OPERATIONAL

FOR UP TO DATE INFORMATION PLEASE SEE THE LINK UNDER THE FULL TG LIST TAB AS WELL AS AGAINST EACH REPEATER LISTING UNDER THE REPEATER TAB

Despite the talk group restructuring having been completed, there could be some “fine tuning” to be done over the next month (and beyond) as Keepers can request additions and removals. We will keep posting updates on the relevant pages on this site as well as via the Facebook page and Twitter. Also via our weekly newsletter

~~~~~~~~~~~

An update from the c-Bridge Admins

** As of 09/01/2016 the process mentioned below has now been completed and hold-off timers are now operational on all wide area talkgroups **

As promised we have started adding hold-off timers to the wide area talkgroups on Timeslot 1. This has already been implemented on the new regional 8xx groups on Slot 2.

‘Wide Area’ means TG1, TG2, TG13 and TG235. As has always been the case these 4 talkgroups will still normally be heard on all repeaters. Users can continue to use them as they always have.

If a repeater user makes a transmission on one of the user activated talkgroups (TG80, TG81, TG113, TG123, TG119, TG129) or local TG9 then the 4 wide area talkgroups will be turned off on that repeater for 10 minutes (5 minutes for TG9). This will allow a user activated or local QSO without the risk of being interrupted by the wide area groups.

The wide area talkgroups remain active and usable on all repeaters not involved in the user activated QSO. Any of the wide area talkgroups can be reconnected immediately without having to wait for the timer to expire by keying up on that talkgroup.

A similar scheme will be implemented on the slot 1 special talkgroups such as 803. TG1 and TG235 are currently working as above. TG2 and TG13 will follow shortly

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TALK GROUP 8xx (ROAMING)

Repeaters will be assigned a “home” region which is always on and is based on the repeater location. Secondary regions are available as a User Activated option. The reasons for the change include (1) it allows linking of repeaters with coverage in multiple regions (2) allows for qso’s to continue should a user go into the next region subject to availability on the next repeater (3) allowing the split of regions such as SE England which has grown to big for TG8

TG800 – RESERVED FOR FUTURE USE

TG801 – METRO EAST (HERTFORDSHIRE / EAST LONDON / ESSEX / KENT)

TG802 – METRO WEST (CENTRAL & WEST LONDON / SURREY / SUSSEX)

TG810 – SOUTH WEST ENGLAND (THAMES VALLEY / BRISTOL CHANNEL / SOLENT)

TG820 – NORTH WEST ENGLAND

TG830 – MIDLANDS

TG840 – EAST OF ENGLAND

TG850 – SCOTLAND

TG860 – NORTH EAST ENGLAND

TG870 – WALES & MARCHES

TG880 – NORTHERN IRELAND

TALK GROUP 2350 – 2353 (SPECIAL LINKS)

These groups will change talk group number – their function remains the same – their new TG number basically puts them within a “regional” block

The repeater listing will show “current special links” and “revised special links”

TG803 – Replaces TG2352 (GB7AK, GB7EP, GB7EX, GB7HR, GB7IK, GB7LO, GB7NS & GB7SE)

TG821 – Replaces TG2350 (GB7HM, GB7FW & GB7LP)

TG822 – Replaces TG2353 (GB7BR, GB7CA & GB7PN)

TG841 – New Talkgroup (GB7DS & GB7MK)

TG862 – No change to this talk group (GB7HS, GB7HX, GB7LE, GB7MR & GB7TD – M62 MOTORWAY)

TG871 – Replaces TG2351 (GB7HM & GB7PN)

UK ONLY USER ACTIVATED UK WIDE

To help with nation wide QSO’s especially as direct dial is suited for one to one QSO’s, two UK Wide User Activated talk groups are being implemented.

TG80 – UK Wide User Activated 1

TG81 – UK Wide User Activated 2

DIRECT DIAL (TG901 – TG940)

All direct dials will be removed from the network as part of the change and the UK Only User Activated Talk Groups can be used in it’s place.

USER ACTIVATED TALK GROUPS

The c-Bridge admins are working to add “hold off timers” which will assist users of these talk groups to hold on to the talk groups by inhibiting the other talk groups from taking the slot if the User Activated Talk Group is in use on a repeaters. This will be a new function that will be worked on to make using the UA talk groups easier for all.

CC-3 dot NET

Paul Leicester | MØFOX | Chesterfield UK | IO93HE | Icom IC-7300

REORGANISATION OF UK REGIONAL TALKGROUPS

UK-Talkgroups

As most of you will know, we have been making various mutterings for many months now regarding the need to reorganise the current “TG8” regional talk group structure. To a great extent, this has been a victim of its own success, but it has shortcomings – some of which we have attempted to paper over with the invention and implementation of the “direct dial” talk groups.

With the rapid (and continuing) expansion of the network it is time for a fresh look at what we might do going forwards; this paper is intended to be the cornerstone of an open discussion regarding how the regional talk groups would be best organised . This is NOT a “done deal”, nor a fait accompli. Please feel free to share thoughts and observations and to ask questions…….

Paul Leicester | MØFOX | Chesterfield UK | IO93HE | Icom IC-7300