NASHUA AREA RADIO CLUB TECH NIGHT SOFTWARE DEFINED RADIOS MARCH 8 TH, 2016

Transcription

1 NASHUA AREA RADIO CLUB TECH NIGHT SOFTWARE DEFINED RADIOS MARCH 8 TH, 2016

2 Software Defined Radios (SDRs) Topics for discussion What is an SDR? Why use one? How do they work? SDR Demo FlexRadio 6000 Series Interfacing To Other Equipment and Software Amps, Band Decoders, etc. Loggers, CW and Digital Modes with SDRs SDR Dongle Demo An inexpensive way to get started SDR Add-on for Conventional Radios 2

3 Software Defined Radios Examples Many Hardware Options Many Software Options 3

4 The Computer Revolution Off-line applications Calculators Logbooks User-defined Radio e.g., HT memory and mode uploads User-controlled Radio Read status from rig Read/write (status and control) e.g., Ham Radio Deluxe, CT, N1MM, RoverLog, 4

5 More Computer Revolution Digital Signal Processing Filters PSK, RTTY demodulators Skimmers Software-Defined Radio MOST All non frequency-determining processes done as logic or equations There is a distinct difference between a radio that internally uses software for some of its functions and a radio that can be completely redefined in the field through modification of software. The latter is a software-defined radio. AC5OG (now K5SDR), QEX Jul/Aug

6 Software Defined Radio What s It Buy Me? More ideal function Better performance Expanded functional capability Was: selectable. Now: continuously variable Was: swept display. Now: continuous display Improved Situation Awareness Understand what is on a band and where it is Updates equal new capability New modes New filter types e.g., Tracking Notch Filters 6

7 Situation Awareness Integrated Bandscopes of the 2000s Near real-time style Swept secondary receiver Displays area around tuned frequency ± 12.5/25/50/100 khz Medium resolution Swept at moderate rate Icom IC-756PRO 7

8 Situation Awareness Digital Sampling/Processing/Display Goal: continuous, real-time display Physical accessory or software GUI Still captures IF spectrum Elecraft K3 and P3 Panadapter 8

9 Situation Awareness - SDR Digital Sampling/Processing/Display Continuous, real-time display via Fourier transform of entire IF bandwidth High resolution In both frequency and time Waterfall provides activity history Adjustable intensity Visual Enhancement allows pulling signals out of the noise 9

10 Software Defined Radio Architecture Variants RF Down- Convert, Detect Sound Card Software RF Downconvert D/A Convert Software Single Conversion Designs Flex-3000, Flex-5000, Apache Labs, RFSPACE, Dongles RF Downconvert D/A Convert Software RF RF D/A Convert D/A Convert Software Software PC Client Buttons & Knobs Direct Sampling Designs Flex-6000 Series, Icom IC Baseband Audio Firewire Ethernet 10

11 It s a Black Box (not really) What s in there? (hardware) RF input-output switching Filtering LO and frequency selection A-D and D-A conversion Computer interface Where s the rest? (software, that s where) Firmware in the box Drivers to connect the box to the computer via FireWire (IEEE 1394), USB or Ethernet Software application or client program in computer performs radio and knobs functions 11

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13 FlexRadio 6000 Series Direct Conversion Architecture Flex Insider August

14 Why All That Math? A diode detects But a real diode isn t perfect The math describes what s supposed to go on Vo = 0, (Vi < 1) Vo = 1, (Vi >=1) 14

15 What s This I/Q Thing? I and Q both sample incoming signals Q Channel is shifted 90 o from I channel Effectively separates frequencies above and below LO Doubles radio pass band for a given sampling rate Makes sideband demodulation a snap 15

16 Filtering in the Digital Domain Simplest design is Finite Impulse Response or FIR Implemented by added scaled & delayed versions of a signal Software applications exist to determine coefficients With today s digital processors, digital filters can be very close to ideal Roll-off sharpness Pass band ripple Phase shift 16

17 Software Defined Radios Key Elements Effecting Performance Architecture Minimize use of analog components Single Conversion vs. Direct Sampling A/D Converter Resolution, Ranging and Speed 12-bit, 16-bit, 24-bit,. Resolution Converter ranging algorithms Sampling speed determines radio bandwidth Panadapter Bandwidth (96 KHz 14 MHz) Precision and Accuracy of Digital Clock Stable, temperature compensated clocks Determines phase noise performance GPS Disciplined Oscillators or GPSDO s (especially for UHF and above) Processing power in box Number of simultaneous Panadpaters (1 8) and receivers 17

18 Software Defined Radios Interface Between the Box and the Computer Interface Bandwidth Distance Remotable? Availability on Recent PCs Analog Audio ~1.5 Mbps Few Feet No Sound card using I/Q Firewire Mbps Few Feet No Not native Ethernet 100 Mbps 1 Gbps Worldwide via Internet Excellent Native USB3.0 Up to 5 Gbps Few Feet No Native PC Internal Limited by bus Same Box No Custom PC Information on the interface can include: I/Q digital data streams Radio control interface (e.x. CAT Interface) Interface speed can limit panadapter bandwidth in many direct coversion designs Native interface support on PC is highly desirable Thin-client designs using ethernet may be a sweet spot 18

19 Remote Operating With An SDR Office Desktop 19

20 Flex-6700 SDR Operation Demo Scenarios Phone QSO PC Running SmartSDR Multiple Panadapters ( slices and receivers) Remote via the Internet Tracking Notch Filters Flex-6700 SDR CW QSO Digital QSO 20

21 Flex-6700 in Operation Phone QSOs, Split Operation, Multiple Panadapters, Filters US Phone QSO on 20m 5J0P DXpedition Split QSO Multiple Panadapters and Receivers Tracking Notch Filter (TNF) 21

22 Flex-6700 in Operation CW QSOs, CW Skimmer, Digital QSO 2015 CW Sweepstakes Contest Digital DX QSO VK9WA DXpedition Pileup on 30m CW 22

23 Software Defined Radios Interfacing to the Other Equipment To Antenna Switching Shack Remote Site Elecraft 500W Amp & Tuner FilterMax BPF A1-6 Local audio via PC Elecraft W2 Power/SWR Meter Band Data, PTT & INH PA Port To microham Control Bus A Port Software Apps Remote: Rotator Control Power/SWR Meter Amp/Tuner Control Antenna Selection (custom) Heil PR781/ USBQ FlexRadio Maestro Bose Bluetooth Headset Flex-6700 SDR microham SND Band Decoder PTT & INH DDUtil Creates Physical CAT Interface WiFi GW g/n LAN Remotes Audio, CW, CAT, UI and COM Ports 1 GBps Switched LAN WAN GW (100/5 MBps) 23

24 CW Operation CW Skimmer DAX (Digital Audio Exchange) LAN Carries Audio, CW, AT, UI and COM Ports Flex-6700 SDR Local audio via PC Virtual Audio Cable Receive I/Q Stream PTT & INH SDR-Bridge Connects DAX and CW Skimmer 24

25 Digital Operation and Logger Interface DXLab Suite DAX (Digital Audio Exchange) LAN Carries Audio, CW, AT, UI and COM Ports Flex-6700 SDR Local audio via PC Virtual Audio Cable Tx & Rx Audio Stream DXLab WinWarbler PTT & INH SDR-Bridge Connects DAX and CW Skimmer Virtual CAT Cable DXLab Commander 25

26 RTL-SDR Dongle Operation Demo Scenarios Overview of the Hardware and Software RTL-SDR Dongle and Antenna Package Ham in Up Upconverter SDR-Radio Software Receive FM Broadcast Radio 2m Simplex FM 2m Repeater Monitoring Weather Band Radio Pager Channel Reception Setup guide

27 SDR Add-on for Conventional Radios Example - RFSPACE SDR-IQ USB IQ + Control IF Output SDR Connects to IF output of conventional radio Use SDR-RADIO software to display IF in SDR format on computer SDR-RADIO uses CAT interface to tune conventional radio based upon SDR inputs 27

28 Additional Topics for Discussion Open Source SDR Programs available New Icom IC-7300 Direct Sampling Radio Contesting Possibilities with SDRs Advanced Digital Modes with SmartSDR SDR Performance Measurements Reciprocal Mixing Dynamic Range (RMDR) and Phase Noise 2:00, 5:00, 8:45, 12:30, 28:15 mins 28

29 Useful Links FlexRadio - RTL-SDR - RFSPACE - SDR-RADIO - Signal ID Wiki - Sherwood Radio Performance Comparisons