Going Digital – How did we do it by Jason 2E0XTA

Going Digital – How did we do it?

Digital Communications, they are all around us – however, despite all these technological advances, I’d say with some confidence – your using FM as your Primary or only mode for RAYNET Communications? So you might be thinking now, why should I change if it just ‘works’ and is readily available on every Amateur Radio on the market?

I used to think the same, then I was co-opted as the Engineering Officer of Essex RAYNET and a short-while later, an Emergency Planning Officer asked me something I wasn’t ready for – ‘What is your Capability for Passing Voice Messages Securely over your Radio Network?’, slightly bewildered, subsequent discussion determined a ‘Requirement’ for ‘Secure’ Radio Communications for Sensitive Information which the EPO would need us to pass, being established. This was then followed by subsequent requests from other EPO Teams and User Services. A clear need was developing for Secure Communications from RAYNET.

So, how to solve this problem?
We could use Scramblers on FM, which would help to a degree, however is a very old school method which isn’t proven to be that reliable.
We therefore looked at the various Digital Voice Technologies available – those being D-Star (Amateur, however offers no Encryption), DMR (Encryption Available) and NXDN (Encryption Available) – so with D-Star eliminated, we narrowed it down to DMR and NXDN.
Essex RAYNET already at this time, had a small fleet of VHF DMR Radios & Repeater.
A number of its Members also owned DMR Radios which were either Dual Band or UHF (which was our preferred Band for a solution).

DMR was also our preferred Mode of Choice as it allows for simultaneous use of both Time Slots – meaning you can RX/TX on Time Slot 1 & 2 via a DMR Repeater at the same time – this was very important for us, as we didn’t want a situation where a Secure Message could not be passed because the ‘Channel’ was in use – a common problem with FM & NXDN (with 1 Repeater) where you essentially have 1 Channel per 12.5kHz frequency, where as with DMR, you are getting two channels via the Time Slots – if you use 2x NXDN Repeaters you get 2x Channels within the 12.5kHz Spacing as they are 6.25kHz each.

What about Encryption?
We looked at what Encryption was available from Amateur Equipment, such as Anytone, TYT and Retevis – we soon determined that while there was various options available, none of them would work reliably enough with one another to such a point where the Make/Model or Firmware wouldn’t cause an incompatibility – Anytone’s are particularly known for issues between firmware versions regarding Encryption. This led us to look at the options available from Commercial PMR Manufacturers such as Motorola and Hytera.

Given our previous experience with Motorola Equipment and after comparing the various options available, we settled on Motorola – this is because it offered us Basic (15 bit) and Enhanced (40 bit RC4) Encryption by default, Accessories are widely available, with good Build Quality and range of Models.

Buying Equipment?
In late 2019, we were able to purchase a Used DR3000 UHF Dual Mode DMR Repeater, 6 DP3400 Handhelds and 1 DM4400e Mobile – this was enough to get a basic network established within an incident.

We later were able to purchase an additional 6 DP3400 Handhelds and 2 DM4400e Mobile Radios to bolster the RAYNET Fleet available for use by Members.
Additionally, we helped advise Members of what Motorola Radios to purchase if they should wish to – many did, currently 50% (21) Members own UHF Motorola Secure Handhelds and 25% (10) own UHF Motorola Secure Mobiles.
Currently 75% (32) Members own a UHF DMR Handheld Radio.

As we all know, COVID-19 Pandemic meant most of 2020-2021 was a difficult time for Groups – however we were able to use this time to develop our Digital Strategy, Radio Codeplug and refurbish the Trailer Mast.

Trialling DMR for Real!
Our first deployment of DMR and Secure Communications, was the Clacton 150 Fly Past in 2021 – a 2 Day Event, which requires Essex RAYNET in a pre-deployed ‘State’ to support the Emergency Planning Team with Resilient Radio Communications between the District Emergency Response Centre, Silver-Bronze Command and Event Control – we typically pre-deploy Operators additionally along various points along the Sea Front to provide ‘on-the-ground’ reports and to assist with swift redeployment in the event of a Major Incident.

Given the nature of the Event, we utilised this as our first opportunity – following a request from the EPO for Secure Communications – to test the Resilience of DMR and decided to roll with a Dual Net – Analogue FM for Routine Traffic and DMR on a dedicated Time-Slot for Secure Traffic to be passed – this worked very well!
We deployed 12x RAYNET DP3400s, our DR3000 Repeater on our Trailer Mast and a backup DR3000 at another location – some Members also used their own Motorola UHF DP Radios.

DMR was able to operate from within buildings where, FM Analogue did not work and would require a ‘Talk-Through’ Repeater to be operated from the Car Park to get Reception into the Radio Network. This was a big bonus – as it meant we could save deploying resources needlessly and benefit from improved Audio Quality, Caller ID via the Radio Display and the ability to Pass Voice Messages Securely using 40 Bit Encryption.

It is important to note that the Repeater was in ‘Dual Mode’ so whichever ‘Mode’ it detects when a transmission is received, it will be in that mode until the Transmission has finished, then will go back to ‘Standby’ – this means that while you could use Timeslot 1 & 2 on DMR simultaneously, you cannot TX/RX DMR & FM simultaneously, its either FM or DMR.

Following on from this success in August 2021, we deployed Simplex DMR on a PMR basis at the Net Control of the Cycle for Life in September and Chelmsford Marathon in October – once again the audio clarity of DMR and ability to ‘Encrypt’ if required by the User Service (who was present at both events) was a useful feature.

Between October 2021 and January 2022, we went onto make small adjustments to the DMR Codeplug/Repeater to improve efficiency and enable features such as ‘Emergency, Text Messaging and Radio Check’ and allow for a Standardised 16 Channel Codeplug that is shared between the DP3400s, DM4400e’s and DM4600e Radios within the Essex RAYNET Fleet – similarly, a Codeplug listing was made available for the Membership for those who wished to add the Codeplug without Encryption to their Radios.

To maintain the Security/Integrity of the Encryption, the key is changed at regular intervals and/or when a Member with a Secure Radio leaves the Group.

Our first Full DMR Event!
Our next full deployment of DMR, was the Clacton Airshow in 2022 – which would see Essex RAYNET go fully Digital/DMR for all Event Radio Communications.
Like in 2021, Essex RAYNET were pre-deployed to strategic locations, where we expected and were required to pass Sensitive Information, on behalf of the Emergency Planning Team.
We deployed 12x DP3400s for Operators to use, 2x DM4600s at Net Control, 2x DR3000 (1 Primary and 1 Backup) and some Operators used their own DP3600/4800 Handheld Radios.

To utilise DMR fully, we operated a ‘Secure’ Encrypted Net on Time Slot 1 and a Routine Radio Net on Time Slot 2 – Operators would either be notified to switch to the Secure Time Slot ready to TX/RX Traffic by Net Control or would call through Immediate/Secure Traffic to Net Control on Slot 1 Secure, who had 2 Radios monitoring both Time Slots, with 2x Operators per Radio/Time Slot.
This again worked very well and enabled for simultaneous Radio Traffic when required, while maintaining the Security of the Sensitive Information which was required to be passed during the Event. We noticed the Range to be as good, if not better than Analogue FM.

How do you distribute your DMR Equipment?
Good Question – following Equipment Donations from Members, an additional 6x DP3400 Handhelds and 1x DM4600e Mobile Radio, allowed for an even distribution of DMR Equipment across the three Counties of Essex.

This now means that across the 3x Areas of Essex, North – Central & South, each has access to 6x DP3400 UHF Handhelds and 1x DM4400e UHF Mobile, for use at Events and or Incidents where Secure Radio Communications or PMR Radio maybe required.

What are the next steps?
Further development of our DMR/Digital Strategy, which is likely to include the ‘linking’ of DMR Repeaters via Mesh Networking to allow for Very Wide Area Coverage and the use of multiple DMR Repeaters simultaneously.
We would also like to see us work with neighbouring groups to ensure we can work with them on DMR, wither this be through a shared codeplug or devices etc to facilitate this.

Is File Transfer/Chat available on Motorola DMR?
Yes – we have conducted some small scales tests using ‘SmartPTT’ Server and Client, over a distance of 20 miles, which allowed for file transfer with and without Encryption, albeit at 1150 Bit/s – which isn’t fast but does work. Using a Terminal Program, it is entirely possible to make use of the connection between Radios (Motorola DMR Radios connected via Cable or Bluetooth, are treated as Network Devices) for sending basic text between Terminals.

Has DMR replaced FM in Essex?
No, FM remains our Primary Voice Mode, at Events or Deployments where Encryption isn’t required or it would not be practical to deploy DMR.
It is our intention to use utilise DMR more in the near future at Events & Deployments, with FM always being available as our Backup, either via the Dual Mode Repeater or Simplex.
Essex RAYNET currently has a significant FM Crossband Repeater Network which covers most of the County, there are no current plans or ways we can convert this to DMR at this time.

Alternatives to DMR?
NXDN from Kenwood and Icom is a worthwhile technology worth considering if you are not a fan of DMR or feel that your budget would not stretch to Motorola prices, however its worth remembering that while it is cheaper, to get the benefits such as ‘Two Time Slots/Voice Channels’. If you are looking for a simple way of adding Encryption to your capabilities and only need 1 Voice Channel, IDAS NXDN could be for you – Repeaters start around £900 and Handhelds such as the ICF-2100D for around £200.

Closing Thoughts
Whichever path you end up going down, be sure to involve your Membership along the way – you may be surprised to find that they want to be part of finding the solution!
Remember, you don’t have to buy NEW, there’s a good Used Market out there for Commercial PMR Radios (Giving you the ability to use Amateur & PMR at will), which typically has great build quality and features you don’t get in Amateur Radios which may be useful.
Essex RAYNET began looking into Digital Technologies long before I was even a Member, exploring early NXDN/IDAS, DMR and Mesh Networking, unfortunately due to a lack of ‘buy-in’ from its Membership at the time, it didn’t move forward enough to the point where you have the solution – takeaway from this, if you think you have the solution, keep pushing!

Hopefully this has given you a brief insight into how we in Essex RAYNET, tackled the problem of going Digital and providing Secure Radio Communications.

2E0XTA Jason Moore
County Controller for Essex RAYNET since 2021 & Engineering Officer 2019 – 2022