September Updates

Over the past few months we have released two new demonstration videos, and there have been some user uploaded videos demonstrating the KrakenSDR in action as well.

Low Power FM Transmitter Hunt

In this first video from us, we used a KrakenSDR to determine the location of a low power FM transmitter that was not complying with the rule that says the station must periodically broadcast contact information. Without that information it was not known where the station was broadcasting from.

The KrakenSDR was able to find the station easily, pinpointing it to within a few meters.

GSM Multi-VFO Demonstration

In the second video from us we used a KrakenSDR and the multi-VFO feature to simultaneously collect bearing data on multiple GSM towers. Simultaneously collecting data made finding each transmitter successively faster.

KrakenSDR and DF Aggregator connected over a one kilometer 802.11ah WiFi Link

In the next video Aaron (creator of DragonOS), and [@VibesGoon](https://twitter.com/VibesGoon) on Twitter/X teamed up to test a KrakenSDR connected to a SteamDeck device, which transmitted bearing data to a PC via a long range 802.11ah WiFi link. The 802.11ah worked well at up to a kilometer away.

Image Credit: https://twitter.com/VibesGoon/status/1667603757549383680, https://twitter.com/VibesGoon/status/1672441902400929793

AREG Fox-Hunt

In this video Mark Jessop used a KrakenSDR and his custom LED HUD to locate an amateur radio fox hunt beacon.

Radiation pattern tests on KrakenSDR antenna from antennatestlab.com

Antenna Test Lab (antennatestlab.com) have kindly provided us with radiation pattern tests for our KrakenSDR antennas.

The graph below can be useful for determining what antenna length to use for what frequency, especially as the KrakenSDR antennas contain a loading coil to improve the lower frequency response, so they are not exactly 1/4 wavelength antennas.

Software Updates

Android App Updates

The Android App will be soon updated to a new version in order to comply with Google Play API level requirements. This also requires the MapBox API to be updated to the latest version too, so you may notice some minor changes to the UI.

The new version of the app also includes some improvements such as significantly faster heatmap generation times (now even large log files load quickly), night maps mode, outdoor/terrain map tiles, and improved auto-zoom mode, the ability to hold the heading when the speed drops below a certain value and the ability to avoid toll roads and highways when turn by turn navigation is being used. Some convenience features like being able to copy the lat/lon and open a location up in Google Maps (for example to access Google Street View) has been added to the long press menu as well.

KrakenSDR Web Mapper Updates

The cloud mapper at [map.krakenrf.com](https://map.krakenrf.com) has also undergone several significant updates since our last posting. The UI has been improved and made significantly faster and more responsive, and minor annoyance issues like the heatmap constantly flashing in previous versions have been fixed. An issue with heatmap decay not working correctly sometimes has also now been fixed.

There is also now the ability to share data from your KrakenSDR's within a group. This allows groups of users to work together to determine the location of an unknown transmitter.

The cloud mapper is reaching a more stable status, so if you haven't checked it out yet please do!

Orange Pi 5 Image Released

We have also now released a ready to use image file for Orange Pi 5 devices. The Orange Pi 5 is an excellent device that runs the KrakenSDR very smoothly due to it's fast processor. A link to download the image file can be found on our Wiki https://github.com/krakenrf/krakensdr_docs/wiki/02.-Direction-Finding-Quickstart-Guide#burn-sd-card-image

Core Software Updates

Thanks to third party contributors on GitHub our core software has been updated to add an auto squelch feature which should work in most situations. Squelch is used to prevent random bearings being generated when an intermittent signal stops transmitting. Setting the right squelch level can be challenging especially if the noise floor is changing in different environments, so auto squelch is a welcome improvement.

Finding Multiple GSM Base Station Transmit Towers with the Multi-VFO Feature

In this video we're using KrakenSDR to find the location of GSM base station transmit towers for four frequencies. We're also using the multi-VFO feature to capture the bearing data of these four frequencies simultaneously which can save us some search time.

Once we've found the first transmit tower, we already have some logged bearing data that can be used to help us find the second tower faster. Then the third and fourth towers are even faster to find due to even more data having already been collected.

Interestingly, it also turns out that the first frequency we search for is actually being used by another tower that we pass along the way back. The location of this tower was picked up on the drive back to the first tower. It's possible that these two towers which are a few kilometers apart are covering different areas with directional antennas.

Also note that the first two transmitter searches use the "auto-zoom" map camera feature, which will automatically zoom the screen to show both the vehicle and estimated transmitter location. The second half uses the standard free camera mode.

This is on a new build of the App which is currently in testing, so some things may look slightly different to the currently released version. The new app version will have some minor feature improvements.

KrakenSDR Low Power FM Transmitter Hunt

In this video we are using a KrakenSDR to hunt for the location of a low power FM transmitter (LPFM) station at 106.7 MHz. These low power FM transmitters are legal as unlicensed transmitters as long as they operate under certain restrictions, the main one being that they transmit at under 1 watt EIRP. LPFM stations are typically operated by local communities or niche radio stations.

Because they are unlicensed, there is no official record and their location doesn't show up in the radio spectrum management database. A requirement of LPFM is that the station broadcast the contact information of the owners regularly, but it can be difficult to locate non-compliant stations that don't do this. But the KrakenSDR makes finding them easy.

The array is 45cm in radius, which is about the maximum that my RAV4 car roof can fit. Some of the antennas sit on a slight curve on the roof, but this appears to have negligible effect. The spacing factor is about 0.19 (optimal is 0.5 - a much larger radius), but even 0.19 is sufficient to find the transmitter fairly easily.