PROPRIETARY STATEMENT: The information contained is this document is Proprietary to DRS Technologies, Inc. “High Performance GNU Radio applications: Super or Zero? : A Trade-off Comparison of Superhet vs. Zero IF Radio Architectures in Real World Environments”

2 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. In other words - Nasty radio environments can produce an undesirable output

3 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. DRS Signal Solutions produces radios that meet GNU standards Zero IF frequency conversion architectures have been proposed to meet the goal of a “radio on a chip” for receivers and transmitters. This presentation examines zero IF and super- heterodyne approaches, comparing the strengths and weakness in dense signal environments. Particular attention is paid to size, weight, power, price and performance. Real-world operational examples are given to highlight the differences.

4 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Agenda Discussion of real world and crowded spectrum issues Review dynamic range terminology…NF, IP3, IP2 & NPR Super-heterodyne and Zero IF …The difference explained How the pros and cons could affect a GNU Radio application Testing and evaluation….On-the-Air vs NPR Conclusions

5 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. The Real World Omni-directional Discone Antenna (30 to 1000 MHz) and Log Periodic Array ( 1 to 3 GHz) 3 Miles South of Chicago

6 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Real World Spectrum Energy- Chicago ………………

7 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Multiple Signals Require Total Average Power and Crest Factor (CF) Considerations.…10Log(#Signals), 15Log(#Signals), or 20Log(#Signals)

8 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Simple and Complex Signals and Their Crest Factors (CF)

9 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Note! Overload of the radio stages before the ADC may require RF/IF attenuation, but the radio control is usually limited to seeing signals in the ADC IF bandwidth. The ADC is blind to signals outside its IF spectrum! What you can’t see can hurt you! Simulate or calculate first!

10 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Calculating CF Signals at Different Levels and Types

11 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Calculating CF on Cellular Spectrums From the above, note RF level and spectral BW of the down links (Cell towers)….about -33 dBm…. over 852 to 864 MHz ~ 22 MHz TDMA signals are channel spaced at 200 KHz. 22 MHz/200KHz = 110 channels About 80 % are occupied… Log 88 = 29.2 dB Add 29.2 dB to -33 dBm = -3.8 dBm statistical peak power – What about other cell bands?

12 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. DRS Signal Solution in Germantown….total signal power + crest factor

13 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. The Real World is Brutal Multiple strong signals in an imperfect radio will create false “spurious” signals that will create useless clutter and interfere with the reception of the desired signal. With many strong signals, the radio may be grossly overloaded and lose sensitivity.

14 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Traditional Dynamic Range Two Tone Tests

15 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Non-linearity in Radios Cause Spurious Issues…IP2 & IP3 Two signals in the non- linear portion of the transfer curve will cause IM2 & IM3 (Intermods)…If a mixer, the spurs can be (Harmonics of RF X LO)

16 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. A Better DR Test for Tuners Working with Real World Signals (Used by the telephone companies for 75 years)

17 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Testing and Evaluation…Real World and Simulation Real World RF Spectra – testing for intermodulation (IM) distortions (spurious signals)…IP2 ~ IM2, IP3 ~ IM3…etc. created by non-linearity in tuner. Noise Power Ratio NPR testing – Substituting controlled noise for multiple signals and looking into the notch to measure IM’s created by non-linearity in tuner.

18 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Real World Spectrum…Detecting RF Intermods & (XRF times XLO) in Tuners

19 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Noise Power Ratio Testing Comparisons 1.Tune radio UUT #1 & #2 to middle of 1 st notch 2.Set SG frequency to tuned radio a level of 10 dB SNR 3. Reduce attenuator (raise noise) until 7 dB SNR 4.Switch out notch and measure noise 5.NPR is difference between step 3 and 4 6.Move tuning to next notch and repeat

20 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Causes of Out-of-Band Noise Inside Notch : Non-linear stages between antenna and mixer/IFA……. 1 st and 2 nd IF responses 1 st and 2 nd image responses All possible third order responses All possible second order responses Reciprocal mix of LO phase noise All M X N mixer combinations that make a 1 st IF response

21 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Super-heterodyne Architecture Rx Tx

22 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Zero IF Architecture Optional BPF Rx Tx

23 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Super-heterodyne vs. Zero IF Pros : High quality fixed frequency IF bandpass filtering 1/f noise at IF is negligible Good image and spurious signal rejection Good (Superior) dynamic range Cons: Higher complexity Larger size Higher cost May be higher power Pros : Low cost, small Simple receiver architecture Baseband filtering can be done digitally or with active filters Cons: 1/f noise is amplified DC offset spur caused by LO rectification in mixer Requires image rejecting mixer – Image (false signal) Tx/Rx spurs about - 45 dB dBc (vs. superhets -90 dBc) Second order distortion, nonlinearity creates a signal at 2f. Both Rx & Tx respond/transmit LO harmonics Superhet Zero IF

24 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Types of Preselection to Reduce Out-of-Band (OOB) Interference Least cost but no 2 nd order protection and multiple signal overload issues 2 nd order protection but loss problems…Higher Noise Figure Most protection from OOB interferers & 2 nd IMs but higher cost and PCB real estate

25 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Issues to Consider… Product data sheets; general specifications do not adequately predict radio performance in the real world. Which of the following matter for your specific application? Cost: A simple lower cost product may fit the need for a specific requirement. – But even with limited frequency applications, zero IF requires a tight preselector BPF to reduce spurious RF environment: Real world spectral evaluation and testing is essential to avoid damage from RF interferers. Many combinations of large signals can produce “Single Signal Spurious”. Spurious signals: The presence unwanted signals in a crowded RF spectrum may result in false signals or interference with desired signals. Performance: It is very difficult to define the metrics to determine “Good Enough” when each surveillance site has varying spectra. Knowledge is key

26 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Zero IF vs. Super-heterodyne: Tuners at low signal spectra (300 MHz) On-the-Air Intermod Spurs A 3 dB change in antenna level resulted in a 6 dB drop in IM’s ….therefore IM2’s SPURS Zero IF Superhet Signal

27 Use or disclosure of data contained on this sheet is subject to the restrictions on the title page. Copyright © 2012, 2015 DRS Technologies, Inc. Proprietary information.. Conclusions GNU Radio provides a framework for very diverse RF application development, including specialized, high-performance designs In high density signal environments, super-heterodyne Tx/Rx have higher dynamic range – Fewer IMs (Spurious signals) Both Zero IF and Superhets benefit from preselection filters that reduce the total number of signals In a low signal density environment, a Zero IF may be OK and less expensive but an RF bandpass filter is recommended On-the-Air testing for IMs is easy but difficult to quantify Noise Power Ratio testing gives the best indication on how radios perform in a high density signal environments vs IP2 and IP3 test

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