GB3JV

GB3JV DATV repeater located in Petts Wood, Kent

Output: 3.404GHz - 2MS/s - DVBS-2 - 0.35 - FEC 4/5 - Horiz. Polarisation

Location: JO01AJ (Petts Wood Railway Station) 

Web Site: http://www.gb3jv.co.uk/

GB3JV Overview

• The repeater uses an innovative new controller system based on the Blackmagic ATEM Mini Pro broadcast switcher and Bitfocus’ “Companion” middleware
• The 70cm and 23cm receivers are based on the “Minitiouner” hardware, developed by F6DZP and the “Ryde” software developed by members of the BATC
• When a signal is received a “web-hook” command is sent to “Companion” and sends an instruction to the ATEM that instigates a MACRO to transition to the active input
• The web stream is generated by the ATEM Mini Pro and the media server is based on Guy, M0GUY’s PiDeck software
• You can register on the web site to receive a stream key and to be included in the GB3JV SLACK channel. SLACK will alert you to repeater activity so you can join in with a QSO.

Telemetry:

The repeater’s  telemetry system is based on the “Modbus RTU” protocol over internet protocol this allows:

• Full remote monitoring of the repeater’s health with notifications to the keeper’s iPhone
• Full remote control of the repeater’s functions and status

Outputs:

• 3.404GHz, 2Ms/s FEC 4/5
• BATC Web Stream: rtmp://rtmp.batc.org.uk/live/gb3jv

Inputs:

• DVBS/S2 1249MHz/Horiz. 333kS/s or 2MS/s, automatic FEC detection
• DVBS/S2 437MHz/Horiz. 333kS/s or 2MS/s, automatic FEC detection
• BATC Web Stream, please limit your stream to 800kb/s
• 144.750 FM/Vertical 103.5Hz CTCSS (ATV Calling Channel Talkback frequency)

Networking:

• The repeater is curently networked using an unlimited 4G cellular tariff provided by "SMARTY" an H3G company.

Latest News (updated 10/07/2022)

Input Recording: In August we are launching a new feature: Repeater recording. Those who have joined the GB3JV web site will be able to access any of these recordings via a link. A great way to review your, and others repeater traffic after the event. See the updated privacy policy at http://www.gb3jv.co.uk/

New Ethernet FWA link: Justin’s been a bit busy installing a new 5GHz link between his house and the GB3JV repeater. The objective of the project is to replace the 4G Cellular internet connection with an RF (Fixed Wireless Access) link back to my house. It’s all about the ROI –  4G Cellular @ £18/month: £120 (equipment) + £50 (License) +£10 (cables) = £180 / £18/month = 10 months.

The link equipment I’ve purchased is the Ubiquiti “LiteBeam” 5AC Gen2. This equipment is often used for Wireless Broadband connectivity in rural areas and can be configured for point-to-point or point-to-multipoint. The photograph shows the installation on my chimney. The cost of the equipment was just £60 per endpoint, including VAT. Supplier: 4gon.co.uk 

The equipment provides an ethernet interface at each end and has a comprehensive management system, shown in the attached screen shots. Measured throughput is 30Mb/s the configuration I’m using is a 20MHz channel running QAM64 modulation schema (remember this is half duplex!). I’ve opted for link resilience over ultimate speed. The unit runs two MIMO (multiple in - multiple out)  “chains” one data stream is horizontally polarised and one vertically polarised. I'm monitoring link performance for a few weeks via my Syslog server instance.

Spectrum Planning: The 5GHz spectrum is divided into three bands:

• Band A: 5150-5350 MHz EIRP 200mW alllowed - no fixed outdoor or airborne use, DFS required above 5250 MHz
• Band B: 5470-5730 MHz 1W EIRP allowed - no airborne use, DFS and TPC required
• Band C: 5725-5850 MHz 4W EIRP allowed - Must hold a 5.8 GHz licence and all terminals must be registered. DFS and TPC

DFS => Dynamic Frequency Selection and TPC => Transmit Power Control

Justin's applied to OFCOM for a Band C “light licence”, but for now he's using Band B. The move to Band C (avoiding the amateur allocations!) will give another 6dB margin due to the higher transmit power and an additional 5dB margin due to the lower noise floor (as measured).

Thanks to Gareth G4XAT for his help with antenna erection!