3 in 1. Panadapter, Station Monitor and portable SDR receiver for less than $10

Transcription

1 3 in 1 Click to edit Master text styles Panadapter, Station Monitor and portable SDR receiver for less than $10 by Relu Jianu NJ9R

2 What is SDR? Click to edit Master text styles Software Defined Radio attempts to place much or most of the complex signal handling involved in communications receivers and transmitters into the digital (DSP) style. In its purest form, and SDR receiver might consist simply of an analog-to-digital convert chip connected to an antenna. All the filtering and signal detection can take place in the digital domain, perhaps in an ordinary personal computer. While there are still good reasons to use some analog components in high-performance gear, the SDR approach is becoming more common in Amateur Radio. (ARRL)

3 What is RTL-SDR? Click RTL-SDR to edit is a Master very cheap text styles software defined radio that uses a DVB-T TV tuner dongle based on the RTL2832U chipset. With the combined efforts of Antti Palosaari, Eric Fry and Osmocom it was found that the signal I/Q data could be accessed directly, which allowed the DVB-T TV tuner to be converted into a wideband software defined radio via a new software driver. Essentially, this means that a cheap TV tuner USB dongle with the RTL2832U chip can be used as a computer based radio. This sort of capability would have cost hundreds or even thousands of dollars just a few years ago. The RTL-SDR is also often referred to as RTL2832U, DVB-T SDR or RTL dongle There are many other software defined radios better than the RTL-SDR, but they all come at a higher price. Currently the Airspy ($199) and SDRPlay ($149) SDR s are the best low cost RX-only SDR s. Then there are the HackRF ($300USD) and BladeRF SDRs ($420 to $650), which can transmit and receive.

4 Inspiration for the project January Click to edit 2016 Master article text by James stylesforkin, WA3TFS

5 Why so complicated? Click to edit Master text styles Portability Unit can be easily powered by any device with USB port or battery. Versatility An all mode all band receiver in the palm of your hand. Simplicity Hardly any components so nothing could go wrong. No adjustments

6 What do I need? HARDWARE An inexpensive DVB-T RTL Stick DVB-T is an abbreviation for "Digital Video Broadcasting Terrestrial"; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television. It transmits compressed digital audio, digital video and other data in an MPEG transport stream, using coded orthogonal frequency-division multiplexing (COFDM or OFDM) modulation. TXCO crystal oscillator Any TTL oscillator over 25 MHz A mixer Any double balanced mixer 0-500MHz or higher SDR Sharp HDSDR SDRTouch SOFTWARE

7 DVB-T RTL Sticks RTL2832U & R820T2

8 TXCO Crystal Oscillator 5V supply voltage since USB port provides the voltage 3.3V is also readily available (see Grand Complications) TTL output Frequency over 24 MHz Why over 24 MHz? RTL-SDR start receiving around 24MHz 24MHz RX 24MHz TXCO = 0 Hz Reasons to choose a whole fixed frequency 50MHz, 100MHz

9 Double Balanced Mixer Can be any DBM, full size metal can or SMD type RF/LO Input or MHz IF or MHz SBL-1 and ADE-1 work equally well SBL-1 ADE-1

10 Software HDSDR or SDR# Sharp for Windows, GQRX for Linux and MacOS, SDRTouch for Android HDSDR has more filters and possibility of adding notches to unwanted signals SDR Sharp is easier to setup Very little tinkering Audio card One free USB port Use a USB extension cable Use shielding or ferrite

11 SDR# Sharp

12 SDR# Sharp

13 HDSDR

14 HDSDR

15 SDR Touch developed by Martin Marinov Application (Play Store) used in conjunction with RTL2832U driver SDRTouch

16 SDRTouch

17 Panadapter A panadapter is device that allows you to visually see the RF spectrum and waterfall being received by your receiver. There are multiple commercial panadapters available, but combined with a PC or laptop, the RTL-SDR will work just as well Only use the straight RTL dongle if your IF is higher than 24 MHz Your radio s IF output gets piped in the antenna port of the RTL dongle Most modern radio provide a LO tap point inside the radio

18 Panadapter

19 Yes, the design requires only three components in addition to the RTL stick. Is it that simple?

20 Is it that simple?

21 SDR Receiver

22 SDR Receiver

23 SDR Receiver

24 SDR Receiver 5V from USB to power TXCO IR sensor on RTL stick Removed IR sensor

25 Station Monitor Able to monitor your station in real time or record your audio for later monitoring, level checking on digital modes especially those used with an audio card checking your bandwidth or effects of various transceiver settings Record functionality already built in the software Ability to play with filters in software to see effect on transmit levels and audio quality 50 Ohm Load on input of RTL SDR Receiver or no antenna connected. Increase attenuation or decrease gain in software.

26 Station Monitor

27 Station Monitor

28 Portable SDR Receiver Uses an OTG (On The Go) cable to connect to your Android phone USB power makes the unit completely portable Current draw is insignificant ~150 ma* (compared to screen consumption) SDR Touch Application (Play Store) Used in conjunction with RTL2832U driver Nice all band general coverage receiver Can be used in an emergency (no power) Fits in your shirt pocket Can be no larger than a flash drive if SMD used.

29 Portable SDR Receiver SDR Touch developed by Martin Marinov Application (Play Store) used in conjunction with RTL2832U driver Can be used with an active antenna, loop or stick (requires 12-15V DC but can use buck boost to convert 5 12v) Internal rechargeable battery with solar panel on the case?

30 Portable SDR Receiver Cell phone with OTG cable and SDR radio

31 Calibration How do you know you re on the right frequency? RTL-SDR can vary from 1ppm to 100ppm and may be temperature dependent. Ways of calibrating: NOT SO GOOD Known AM/FM station GOOD WWV on 2.5 MHz, 5, 10, 15, 20, and 25 MHz CHU on MHz, and MHz GREAT High Precision OXCO Wenzel Associates ( good to 1e-9 / year GPS such as Adafruit Ultimate GPS Breakout - 66 channel GPS w/10 Hz updates

32 Calibration

33 Static sensitive Chips dissipate a lot of heat 52C = 125F 85C = 185F Filtering AM or FM broadcast stations A word of caution

34 Recap DVB - T Dongle based on the RTL2832U & R820T2* DBM SBL-1 or ADE-1 TTL TXCO

35 Recap

36 Grand Complications What is the ideal configuration? Is there one? Adding a low pass filter (0-30MHz, 0-54MHz or 0-500MHz) higher? LED or no LED single dual or tri color? 5V or 3.3V for SMD TXCO ( is RTL regulator IC good enough?) FM trap? AM trap? Adding an antenna switch - how many ports? Shielding each stage? LNA?

37 Grand Complications

38 Grand Complications

39 Grand Complications

40 Grand Complications

41 Grand Complications TTL vs CMOS TTL: High: 2.4V Min. / Rise = 5nS Larger footprint Requires 5V CMOS: High: 90% VDD / Rise = 5nS Should work in theory Requires 3.3v or 5v Could not make it work.

42 Grand Complications

43 Grand Complications

44 Grand Complications

45 Questions? Happy Building

46 Credits RTL-SDR.com - James Forkin WA3TFS- QST January 2016 All-Mode 1 khz to 1.7 GHz SDR Receiver AirSpy (Sharp SDR) HDSDR - SDRTouch - Martin Marinov OXCO - Charles Wenzel of Wenzel Associates