Tag Archives: YateBTS

Dumb Lesson in RF Connectors

RF, , , ,

When the YateBTS project launched 6 or 7 years ago I went out and purchased what was to be my first “real” SDR – The BladeRF x40.

At the time I wanted to play with GSM stuff, and so I grabbed two rubber duck antenna off an Alarm GSM Dialer I had in a junk box, thinking they’d do a better job than the stock “everything-band” antenna that came with the SDR hardware.

The offending antennas

These two became my “probably roughly aligned with the common commercial RAN bands” antennas,

I’ve used these antennas on pretty much all my RAN related projects on the BladeRF, HackRF and the LimeSDR,

  • GSM with YateBTS
  • GSM with Osmocom
  • iPhone connecting to SRS LTE eNodeB SDR
    LTE with srsLTE

I had some issues a recently I attributed to “probably rubbish antennas” so decided to get a pair of paddle antenna tuned for the frequencies I was working with.

While working out what to get I had a look and noted the connectors on all my SDR hardware is SMA-Female connector. Easy, so I need an SMA-Male connector on the antennas, purchase made.

Cut forward to today when the antennas arrive at my door, they’re exactly as described, however I notice some resistance when connecting them, the male pin is stiff to go into the LimeSDR, whereas there’s no resistance at all from my “trusty” rubber duck antennas.

That’s when I realised.

The two antennas I’ve been using for about 7 years at this point, have the wrong connectors (SMA and RP-SMA) and have not made contact on the signal centre pin that entire time…

They’re RP-SMA male and I need SMA male.

Wasn’t just reverse polarity – it was no polarity.

I’m a walking encyclopedia of connectors, acronyms and layer 1 stuff, but apparently this I missed.

I’m an idiot – a lucky one who didn’t burn out his SDR hardware.

An idiot with greatly improved RSSI though…

Configuring YateBTS for Software Defined GSM/GPRS

GSM, Mobile Networks, RF, Software, , ,

I did a post yesterday on setting up YateBTS, I thought I’d cover the basic setup I had to do to get everything humming;

Subscribers

In order to actually accept subscribers on the network you’ll need to set a Regex pattern to match the prefix of the IMSI of the subscribers you want to connect to the network,

In my case I’m using programmable SIMs with MCC / MNC 00101 so I’ve put the regex pattern matching starting with 00101.

BTS Configuration

Next up you need to set the operating frequency (radio band), MNC and MCC of the network. I’m using GSM850,

Next up we’ll need to set the device we’re going to use for the TX/RX, I’m using a BladeRF Software Defined Radio, so I’ve selected that from the path.

Optional Steps

I’ve connected Yate to a SIP trunk so I can make and receive calls,

I’ve also put a tap on the GSM signaling, so I can see what’s going on, to access it just spin up Wireshark and filter for GSMMAP

Compiling YateBTS NIPC for Software Defined GSM / GPRS

RF, Software, , ,

A lot of the Yate tutorials are a few years old, so I thought I’d put together the steps I used on Ubuntu 18.04:

Installing Yate

apt-get install subversion autoconf build-essential
cd /usr/src svn checkout http://voip.null.ro/svn/yate/trunk yate 
cd yate
./autogen.sh
./configure
make
make install-noapi

Installing YateBTS

cd /usr/src 
svn checkout http://voip.null.ro/svn/yatebts/trunk yatebts
cd yatebts/ 
./autogen.sh 
./configure
make install

Defining location of libyate

On Ubuntu I found I had to add the library location in ldconf:

echo "include /usr/local/lib/" > /etc/ld.so.conf
ldconfig

Installing Web Interface for NIB / NIPC

apt-get install apache2 php
cd /usr/src/yatebts/nipc
make install
cd /var/www/html
ln -s /usr/local/share/yate/nipc_web nipc
chmod a+rw /usr/local/etc/yate/