Acurite 592TXR Temperature and Humidity Sensors now decoded by rtl_433.

I've added decoding of Acurite's 592TXR "Tower" temperature and humidity sensors to rtl_433. These are small, inexpensive, wirelesss (433 Mhz), temperature and humidity sensors. The 592TXR has several different model numbers including 06002RM

These are compatible with Acurite's consoles such as the 01512 that I have as well as Acurite's Acu-Link Internet bridge which posts to acu-link's web page as well as weatherunderground. I picked up the Acurite 5-n-1 Weather Station, a console, and the internet bridge because the support for the 5-n-1 had been added to rtl_433 and the package price was pretty reasonable.

There were a number of people interested in decoding the 592TXR, but for some reason, it never got added, so I finally added it and cleaned up the Acurite 5-n-1 weather station decoding. The pull request got merged November 8th, 2015.

I think the temperature only version, the 592TX, should also be supported but I don't have one to test. Please let me know if it decodes successfully or not.

The protocol used by the Acurite 592TXR and the 5-n-1 weather station are very similar. The weather station's messages are one byte longer, but they are basically the same with the same RF signaling characteristics.

Remotely monitor Refrigerator / Freezer temperature with Acurite 986 and rtl_433 (rtl-sdr)

I suspected the thermostat in my basement refrigerator was going bad, so I picked up an Acurite 986 refrigerator and freezer remote thermometer.  The display unit will give alarms if the temperature goes out of range.

I wanted a better picture of what was going on so I figured out the Acurite's 433 mhz protocol for the 986 sensors. I've added support to rtl_433. The pull request was merged November 20th, 2015.

Now I pump the data into rrdtool and see what's going on. I now see how long and often the compressor is running, and how long it times to warm up between cycles. The spikes are the defrost cycles.

Now I can also monitor/get alerted when I'm out of the house.

I'm pretty happy with the Acurite 986 display and temperature sensors even without the rtl_433 decoding.

Acurite 00986 Refrigerator / Freezer Thermometer Protocol

• Includes two sensors and a display, labeled 1 and 2, by default Sensor 1 - Refrigerator, 2 - Freezer.
• Data format: Pulse Position Modulated (PPM), 5 bytes, sent twice, no gap between repeaters
• Start/sync pulses: two short, with short gaps, followed by 4 long pulse/gaps.
• Data Format - 5 bytes, sent LSB first, reversed
• TT II II SS CC
• TT - Temperature in Fahrenehit
• integer, 
• MSB = sign. Encoding is "Sign and magnitude"
• II - 16 bit sensor ID changes at each power up
• SS - status/sensor type
• 0x01 = Sensor 2 (
• 0x02 = low battery
• CC = CRC (CRC-8 polynomial 0x07, little-endian) 

I was able to easily figure out the CRC with CRC RevEng..

Another Yaesu VX-8DR external GPS with an Arduino/ATmega328 translator.

I've collected links for a few of these projects to add a better external GPS to the Yaesu VX-8DR, instead of the somewhat proprietary Yaesu option.

Here's another one from VK3YY that got posted recently:

• https://vk3yy.wordpress.com/2015/07/24/vx-8dr-and-gps/ 

Here's code from DFannin on github:

• Arduino code for buidling Yaesu VX8r Handheld Transmitter-compatible GPS

Update 2016-01-15, 4Z7DTF notified me about his project, which includes more additional analysis of how poor the VX-8's parsing and error handling is.

•  4Z7DTF's VX-8 Arduino GPS interface on github 

Background Info:

Good detailed blog post Reverse Engineering the Yaesu VX-8DR GPS Interface. From Feb. 2013. He didn't arrive at the solution, which I believe F4FXL and at least one other have. But I think he's got most of the relevant details for the padding differences listed as well as some other very useful info including details on the GPS chips used in VX-8 and VX-8G.

We now know how to connect to and send a properly formatted GPS NMEA message to the Yaesu VX-8DR. Here's the summary:

• 9600baud TTL 3.3V serial signalling, 8/N/1
  • NOT RS232 -5 to +5V signalling -- you need a level converter if that's all you have
• 3-wire physical interface to the following pins:
  

  Pin	GPS Side Purpose	Yaesu Side Purpose
  4	GPS RX	Yaesu TX
  5	GPS TX	Yaesu RX
  6	GPS GND	Yaesu GND

• According to 4Z7DTF (2016-01-15), there is no need for the communication to be bidirectional. Only the TX Data from the GPS to the VX-8 is required.

The messages need to be formatted exactly as follows: Message Type Source Sentence $GPGGA Sample $GPGGA,123223.000,4131.2334,N,00021.1216,E,1,04,02.7,00123.4,M,0051.7,M,000.0,0000*41 Syntax $GPGGA,hhmmss.sss,llll.llll,a,yyyyy.yyyy,a,x,xx,xx.x,xxxxx.x,M,xxxx.x,M,xxx.x,xxxx*hh $GPRMC Sample $GPRMC,123223.000,A,4131.2334,N,00021.1216,E,0000.00,291.33,301011,,*3E Syntax $GPRMC,hhmmss.sss,A,llll.llll,a,yyyyy.yyyy,a,xxxx.xx,xxx.xx,xxxxxx,,*hh $GPZDA Sample $GPZDA,123223.000,30,10,2011,,*55 Syntax $GPZDA,hhmmss.sss,xx,xx,xxxx,,*hh

rtl_433 now decodes DSC 433 Mhz wireless securty contacts

** UPDATE For status bit decoding see rtl_433 DSC Status Bit Decoding **

If you have a DSC (Digital Security Controls) home security system, with wireless sensors such as door / window contacts, glass break detectors, smoke, CO2, heat, and water detectors, you can now monitor them with rtl_433. The code is now in the mainline Merbanan github repo.

Only the 433 Mhz security sensors/contacts devices are currently supported.  I will be working on other devices soon. I have almost all of the status bits worked out. I will be submitting a pull request soon.

DSC alarm systems are also sold under other brands such as ADT Pulse, and a number of cable/telephone company's home automation systems, such as Time Warner Intelligent Home. DSC is a division of Tyco, so you will also see DSC products listed as Tyco Security, though Tyco has a whole list of security brands.

These are fairly inexpensive wireless devices that can also be useful for a variety of home automation projects.

The DSC WS4945 - Wireless Door and Window contact can be used as a magnetic contact or used with any sort of sensor that provides a normally closed output. If you are using it for home automation without a security system, it doesn't matter if it is normally closed or normally open. It will transmit at any state change. The device also sends a heartbeat with the current state every 64 minutes.

The Vanishing door/window contact, EV-DW4975 is quite thin and small if you don't need the screw terminals for wiring up some other type of sensor. It will barely be noticed on most doors and windows.

If you are interested in decoding DSC's wireless protocols, or have any information to share, please contact me, I could certainly use someone to collaborate with.

** UPDATE For status bit decoding see rtl_433 DSC Status Bit Decoding **

Popular Electronics Magazine archive online 1954 - 2003

A piece of electronics history:

Popular Electronics Magazine issues from 1954-2003 are available on line.  

Might be old news, but I just saw this circulating on a few mailing lists.

This is the first time I recall seeing a reference to this web site, American Radio History.

http://www.americanradiohistory.com/Popular-Electronics-Guide.htm

Popular Electronics was created in 1954 by Ziff-Davis Publishing for an audience of electronics hobbyists and experimenters. It soon became the "World's Largest-Selling Electronics Magazine". The circulation was 240,000 by 1957 and exceeded 400,000 by 1963. Rival Electronics World was merged into Popular Electronics in 1972.

Popular Electronics became Computers & Electronics in November 1982; and then ceased publication in April of 1985.

The title returned in February 1989 under the ownership of Gernsback Publications which purchased the name and gave it to their Hands-On Electronics magazine. Popular Electronics ceased publication in December of 1999, returning as Poptronics in January of 2000 after merging with Electronics Now. The final issue was  January, 2003.

 Enjoy.

New Toys: Getting Deeper into Software Defined Radio (SDR) (AirSpy and HackRF Blue)

This is mostly a tease / place holder.   Around Christmas time I decided to get deeper into Software Defined Radio (SDR).  So I ordered an Airspy and a Hack RF Blue.   So far, I've received the AirSpy and am enjoying it very much.  The Hack RF Blue should hopefully be here soon.

Previously I've been using the $15-20 RTL-SDR dongles.  These are very cheap and useful, but plagued with lots of noise, frequency inaccuracies and other problems.  Still they are a great way to get started and start learning.

The AirSpy is a world of difference from the RTL-SDR dongles.  One of the reasons that I bought it was  a number of people who seemed to have deep RF engineering backgrounds seemed to be pretty excited about it.  There are many good reviews available.

I ordered the HackRF Blue to experiment with GNU Radio and especially try some of the transmission capabilities for digital RF hacking.  Initially I'll probably be doing further experiments with simple 433 Mhz devices.

I expect based on receivers that the HackRF's receiver will not be as good as the AirSpy's by a good margin, for sensitivity, selectivity, etc.. However, the HackRF is capable of operating on a much wider frequency range (10 Mhz - 6 Ghz) than the R820T (24 Mhz - 1.8 Ghz) tuner chip inside the AirSpy.

More to come.

Your Radio's Reverse button / Quickiy Checking the Repeater's Input Frequency

[This was originally published on a mailing list, but seemed worth making more widely available.]

Some amateur radios have a "Reverse"(*) button that swaps the repeater input and output frequencies, allowing you to quickly monitor the repeater input and transmit on the repeater output.  When I first started out, I didn't realize the value of this.

The benefits of this feature are:

• You can quickly listen to the repeater input to determine if someone transmitting is close enough for you to use simplex and free up the repeater.
   
• If the repeater isn't working, you can get anyone who is monitoring the repeater's output and is within simplex range, to hear you by transmitting on the repeater's output.
   
• During time of malicious interference or other search operation, if we all switch over to monitoring the input and make note of whether we can hear the transmitting station, we can use the information to figure out roughly what area the transmitting station is in.

And finally, the benefit that is relevant to the original topic, hitting the reverse button on many radios is a quick way of seeing what frequency your radio is programmed to transmit on for a repeater.  Your radio display will need to be in a mode to show the frequency rather than the label.

Check your radio's manual to find out how to activate the reverse feature as the button might have an obscure label.  A few common one:

• Wouxun - It's the scan button.  (A quick press and release).
• Baofeng UV-5 - The * button.  (A quick press and release). 
• Many Yaesus - Home/Reverse, HM/RV, Rev, etc.