Investigating GSM networks available to us using a CLX SIM

In the article we look at which GSM masts are available to us at our location and see which network will give us the best performance. We also look into establishing a data connection using the CLX SIM card and find the location of our PCB using QUECELL locate system.

We had a board hooked up with 2-way comms to a PC whilst developing the speech storage and playback function on our GSM Alarm Speech Dialler ADs (available at http://www.adventcontrols.co.uk).  We took this opportunity to investigate the network infrastructure we are able to acquire here in our office

GSM Dialler

GSM Speech Dialler with PC connection

Firstly, we send the command AT+CREG? which shows us that the modem is connected and roaming.  We are roaming as we are using the CLX SIM which has access to any GSM network in the UK.

AT+CREG?

+CREG: 0,5

 

Next, we send the AT+QOPS? command to get a list of masts the M66 is able to acquire:

AT+QOPS?

+QOPS: 1,”Vodafone”,”Voda UK”,”23415″

1,0062,305E,1A,22,94

+QOPS: 2,”O2″,”O2 -UK”,”23410″

1,53AC,9BDA,27,23,111       (n.b. 9BDA in hex is 39898 in decimal)

+QOPS: 1,”T-Mobile”,”EE”,”23430″

1,090A,9C47,1F,16,664

 

QOPS: 2 shows us we are currently using the O2-UK mast with location code 53AC and CellID 9BDA.  We can also see masts from T-Mobile (part of EE) and Vodafone are available to us (QOPS:1).  With the CellID we can find the mast we are using on a map

 

O2 Mast

GSM Mast Location

 

Earlier we were using an EE SIM, and this forced us to use a mast in the local retail park which is much further away and out of the screenshot above. This resulted in a signal strength of 16 as opposed to 23 from O2. This is the advantage of using the CLX SIM; it allows the modem to choose the most reliable network.

 

Another advantage of using the CLX SIM is that the GSM device will come with the APN set up correctly by default.  The Access Point Name (APN) tells the network which server your equipment can use. Networks will have different APN for different customers like PAYG or contract.  If you select the wrong one you will have no data access. This is the main cause of issues when using our software and emails. Our boards come with the APN settings for CLX pre-programmed which can be used globally.

 

To demonstrate data connectivity with the CLX SIM cards we will make use of Quectel’s Cellular Positioning System.  This will give is the geographic co-ordinates of the PCB even when indoors.  The modem connects, through the internet, to Quectel’s database of GSM masts and then compares the signal strength from each mast to locate the device.

 

Firstly we must tell the modem the APN which will give us access to the internet as follows:

 

at+qicsgp=1,”connect”,””,””                   …the CLX APN is “connect” with no username or password

at+qcellloc=1                                                     …enquire about our current location

+QCELLLOC: -2.861663,53.353088

 

The at+qcellloc command returns our co-ordinates which we can then paste into Google Maps

QUECLOCATE

Using Cellular Location

The position given by the Quec Locate server is about 0.5 miles out with our high gain antenna.  This is towards a worst case scenario situation given that our PCB is buried deep within a building.  If it were outside it would be much more accurate.

We tried again using the internal adhesive antenna we use for our Gold:Mini Intercom and this time the error was about 0.8 miles.  This is because the internal antenna is optimised for 1800MHz masts which are predominantly located in this direction.

+QCELLLOC: -2.863965,53.361809

GSM ALARM LOCATOR

Low gain antenna location attempt

 

To view our GSM products and for live demonstrations please visit our stand at IFSEC 2018.  We look forward to meeting you.

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Numbers Spreadsheet to make adding multiple numbers easy

We’ve created an Excel spreadsheet to assist in adding large quantities of numbers to your Gate opener, intercom or dialler.

It’s available from our Downloads page

Hopefully it’s easy to use but here is a 5 video showing how to use it.

Should I buy a 3G intercom or alarm dialler?

We get asked a lot when the 2G network will be shutdown. In Europe, on the whole, nobody really knows yet.  The general consensus is that the 3G network will be shutdown first around 2020 and 2G as late as 2025.  In some countries 2G is no longer in operation (USA, Australia, Japan, Singapore…) but this is not the case in Europe.

Vodafone-will-not-switch-off-2G-until-2025

old phone

2G Phone

4G is obviously great for data but until recently many phone masts did not support audio on 4G/Long Term Evolution (LTE).  Audio on 4G uses a system developed by Qualcomm known as VoLTE.  Originally 4G was data only and your phone switches to 2G or 3G for calls.  Audio on 4G is really only being implemented now by most networks.

https://www.4g.co.uk/what-is-volte/

So, that leaves 2G and 3G for handling calls.  3G uses 2100MHz in Europe.  In general a higher frequency will result in a shorter range.  Also, on the higher frequency bands, your phone is limited by the amount of power it can transmit to 1W.  For comparison, on 900MHz 2G your phone can transmit 2W of power giving a better range.  The lower frequency of 2G and 4G bands will also penetrate walls better than the higher frequency 3G band.  3G also only has one frequency band allocated to it whereas 2G has two.

Europe-could-go-alone-in-waving-goodbye-to-3g-first

3G phone

Early 3G phone

3G therefore doesn’t really offer anything anymore.  It is slower than 4G for data and the coverage is usually worse than 2G which is why the network space is better allocated to 4G, 4G NB and 5G.

So, should you buy a 3G intercom or dialler?  We were developing 3G products but decided to stop simply due to their limited life-span.  They will work on 2G when 3G is shutdown but why pay the extra for a 3G unit?  There is one reason; in the UK the 3 network only offer 3G & 4G so you can only use a 3G unit on this network.  They may continue 3G beyond 2020 for this reason.  Also you may find you have no coverage in your area on 2G but there is coverage on 3G.  This would of course be a temporary solution for you!

3G Alarm Dialler PCB

3G Alarm Dialler

We gave up on 3G and I would not recommend paying extra for a 3G unit.  We are developing 4G products but these have many extra complications with VoLTE and network specific frequency bands so our 4G units are taking some time to develop – but 4G is the future!  We expect to be first with our 4G diallers and intercoms in Europe.

VoLTE Intercom

4G VoLTE Intercom

For further reading please see:

https://www.mobileworldlive.com/featured-content/top-three/operators-vendors-forecast-long-life-2g/

 

Gold Mini GSM Intercom: production, testing, inspection

Finally we saw our new Mini Intercom enter production.  It uses a new and novel manufacturing technique which required several iterations to get right.  The end result is a solid, strong lump of fiber glass with a pretty black and gold finish – and yes that’s real gold!  At just 4mm thick this intercom has the appearance of a flush mounted unit but is in fact surface mounted; a common trait for all our Gold intercoms.

4mm thick intercom

Side view

The intercom is fully waterproof. We use the gold finish as it is non-corrosive.  The three parts of the intercom are brazed together forming a water tight seal around the unit rather like a copper pipe is soldered to form a seal.

soldering joint x-ray

Solder seal x-ray

After the soldering process we inspect the intercom using an x-ray to ensure the seal has been formed around the entire perimeter of the unit.

QFN x-ray

Processor soldering inspection

Honeywell Accenta/Optima GSM Dialler SMS Sender – Set and Unset Alarm Remotely

Our C4 for Honeywell Accenta & Optima alarms allows you to remotely set and unset your alarm from anywhere in the world.  It will dial, text and email you when the alarm is triggered and armed and disarmed.

New Firmware Testing

Firmware debugging

v6 Firmware Testing

We’re currently testing the new v6 firmware which offers email support along with:

DTMF tones during calls
Event Logging
Daily health check connection to our server
Email support
Email of balance
Reset logs for monitor errors
Compressed firmware allowing new features
Can include the analogue voltages on customised messages
Event Scheduling (Relay On/Off)
On-board RTC

All looking good for shipping w/c 27/02/17!

Gold Mini Intercom Sneak Preview

I thought I’d share this even though it’s not ready to order yet.  We have a new intercom measuring 10cm x 8cm x 0.5cm.  It actually can be 4mm thick but the rear seal adds 1mm for external applications.  This also makes the audio a little nicer.  We screwed it to a white box for the photo!

GSM Door Phone Intercom

GSM Door Phone Intercom

Due to be available mid-January 2017