Software Defined Radio

This site is devoted to the area of Software Defined Radio (SDR), more specifically, the "Softrock" series of technology sampler kits for working amateur radio HF receivers and transceivers. These kits have provided an economical, relatively risk-free, and exciting entry into the SDR tent. This site describes the kits and their availability and is intended to help newcomers who have absolutely no SDR experience ease into the topic with "Heathkit-Like" build instructions and easy-to-digest theory explanations.

Frequently Asked Questions

Bob KC4UAI maintains a very informative FAQ page in the files section of the Yahoo Softrock40 User group (you must be logged into that group to see the file). Bob also maintains a Softrock SDR Wiki that provides additional info on the Softrocks.

new WB5RVZ SDR FAQ page is being set up to capture issues that have been raised in the Softrock40 group (to compensate for the abysmally poor search capability in the Yahoo Group architecture).

Softrock Rigs Documented on this Site

Software Defined Radio receivers and transceivers currently available (and those that are retired, shaded in red) are shown below. Click on the picture to go tothe page(s) describing the kit and its build instructions.

Softrock Kits - an Overview

Background/History

The SoftRock Kits came into being in 2005 based on Tony Parks KB9YIG's experience with an SDR 1000 Software Defined Radio and the series of seminal articles in QEX by Gerald Youngblood K5SDR. The articles can be read by following these links:

The kits were introduced as a low cost technology sampler for Software Defined Radio and Tony continues to offer the kits as such.

Many people have contributed to the design and testing of the various kits to lower the cost of the kits and to improve performance and functionality.

It is estimated that, since the Softrock's inception in 2005, over 10,000 kits have been shipped to builders in about 60 different countries.

What is a Softrock

Softrock is a term for a software defined radio (SDR) which consists of three major building blocks:

  • The SDR hardware (e.g., one of the Softrock kits)
  • A PC running special SDR software (which is free to download - see the "some SDR software" section of Alan G4ZFQ's website )
  • and a stereo soundcard (with one stereo input for RX and, if TX is desired, a stereo output for TX and a second soundcard to deliver the demodulated RX sounds to the PC's speaker)

These pages concentrate on the SDR hardware. All of the softrock rigs currently available provide either RX and/or TX capability for signals either side of a "fixed" center frequency. The term "fixed" is relative. It means that, when working on a particular band, the SDR's local oscillator produces an unvarying frequency that anchors a "chunk" of RF bandwidth within which you can operate. Some of the Softrocks allow you to tune the local oscillator to multiple center frequencies; the earlier Softrocks limited you to a crystal-controlled center frequency that was, indeed "fixed" (the crystal was soldered into the board!) The bandwidth provided by these SDRs is a function of the PC Soundcard used. The approximate tuning bandwidth you can get, given a specified center frequency (CF) from the hardware's local oscillator and the soundcard's sampling rate (SR) is a range: [CF - SR/2] to [CF + SR/2].

Production and Retired Kits

Flash! -New Ordering System at KB9YIG.COM

Tony KB9YIG has announced The implementation of a new ordering system. The following is an excerpt from his announcement message:

Today we're starting a new chapter in the SoftRock kit sales. Effective immediately, please place all future orders at the web site http://KB9YIG.com. We've begun to automate SoftRock order entry, payment, shipping and status reporting. This transition includes several changes that I'd like to elaborate on.

Going forward, I'm only accepting orders on kits that I have in stock and ready to ship immediately. When a particular kit is out, the web site will note 'check back soon' next to that item, rather than allow it to be added to the shopping cart. While it may be frustrating to find yourself temporarily unable to order a desired kit, I hope that any frustration is tempered by the knowledge that when you do place an order, the item will be put in the mail very quickly.

In conjunction with this, you'll now receive an automated e-mail alert when your kit is marked shipped in the system. By only allowing sales of kits in stock, and by sending an automated e-mail notice when your order is shipped, I hope to consistently meet buyers' expectations regarding delivery.

In the course of building the new system, I had to go through my existing kit component costs and pricing. In some cases, the component prices had remained consistent, providing the small but necessary profit margin required to make this effort sustainable over time. In other cases, the component costs had migrated to the point where when I factored in the PayPal fees and other costs, I was giving away certain kits for free. While trying to maintain pricing as low as possible, I've had to re-price several of the kits in line with today's actual costs. Going forward, kit prices are subject to change as necessitated by component cost changes.

Some of you are volume customers, buying several of the same kit and then turning around and spreading SoftRock use further in your home country. This is very much appreciated. In the past, I've offered quantity discounts to volume buyers in an ad hoc manner, weighing the circumstances and formulating a price in my head or heart. Unfortunately it's hard to automate that level of custom pricing, so we chose to adopt a standard method to acknowledge the bulk buyers. For the time being, the unit price per kit is fixed. However, the shipping cost is adjusted as follows:

  • If you buy one of a particular model, you'll pay the fixed shipping cost assigned to that model.
  • However, the shipping cost is capped such that if you buy two or more of a particular kit at one time, you'll only pay the shipping cost for the first two. For those of you who buy ten or twenty kits at a time, I hope that only having to pay the shipping cost for two units will be sufficient recognition for your valued role in spreading SoftRock use. Any further discount would necessitate raising the base price for everyone else in order to cover costs.

We thought about asking each buyer to create an account as you would on a mainstream e-commerce site such as Amazon.com. However, some of you request shipments to different addresses over time, depending on your current needs and circumstances. Instead of having you create an account, we've elected to have you enter your desired shipping address with each purchase. Please note that all items in a single order must be shipped to a single address. If you need to have items shipped to several addresses, please submit one order per destination. You'll note that every data entry screen after the initial home page is protected by 128-bit SSL encryption using a certificate issued by Network Solutions.

Payment methods include PayPal, Western Union and check/money order. If you choose PayPal as your payment method, you'll be presented with a link to connect to PayPal and may make your payment immediately. If you choose Western Union, you'll receive an e-mail containing a special web link. After making the payment at your local Western Union office, you'll then need to use the e-mail link to submit the Money Transfer Control Number (MTCN) to me. If you choose check/money order, instructions will be shown for mailing your payment.

The kits now available

  • the SoftRock Lite II (monoband) receiver
  • the v9.0 Lite+USB Xtall (multiband) receiver kit and its associated add-on kits:
    • The Automatic Switching 4 Band Bandpass Filter Kit
    • The 6m/2m (and 4m) VHF Converter Kit
  • the one watt RXTXv6.3 (multiband) SDR transceiver kit.
    Note (2/8/2009): after selling the remaining 50 boards, this kit was retired. After numerous entreaties from the SDR community, Tony has placed an order for an additional, but limited number of boards and will announce kit (re)availability in March 2009.
  • the USB I2C interface kit
  • the Delta 44 Sound Card Interface module
  • the XTALL Daughter board
    (an early adoption of the Si570 as a replacement for the local oscillator on earlier Softrock kits)

Softrock Band Coverage - general

Softrock RX and TX provide band coverage expressed in terms of kHz on either side ofa center frequency. In Some of the kits, the center frequency is "rockbound" (i.e., from a crystal oscillator); in the more recent kits, the centter frequency is produced from am Si570 programmable oscillator

Band coverage from each center frequency depends on the sampling rate of the soundcard. With 48 kHz sampling the band coverage is almost +/- 24 kHz each side of each center frequency. If the soundcard can sample at 96 kHz the band coverage is about twice as great each side of each center frequency.

Kits - Description / Documentation

These pages document the construction of seven different types of Software Defined Radio (SDR) and SDR-related kits from Tony Parks' Softrock line. In addition, kinks to documentation of all of the earlier Softrock kits can be found at Cecil's K5NWA website.

  • Receivers

    • SR Lite II - Monoband

      An entry-level, crystal-controlled single band receiver, this is the updated replacement for the just-retired SR Lite V6.2 receiver. This is the receiver you want if you are curious, but cautious and/or frugal. It comes in six "flavors":

      • 160m
      • 80m
      • 40m
      • 30m
      • 20m
      • 15m

      For pricing see KB9YIG.com (prices have been historically in the $10 to $15 range).

      As in its predecessor, the builder's notes for the SR Lite II RX will document the construction by WB5RVZ of the 40m receiver with a crystal-controlled center frequency of 7.056 MHz. Using a soundcard with a sampling rate of 96 kHz, this RX provides a bandwidth of 7.008 - 7.104 MHz.

      For details see the Softrock Lite II home page, which documents the build of each of the six options.

    • Xtall+Lite V9.0 - Multiband

      This multiband receiver replaces the V8.3 receiver. The v9.0 Lite+USB Xtall kit provides an all HF coverage receiver where center frequencies are set via a USB connection to the v9.0 circuit board. The v9.0 receiver has MDS of at least -120 dBm on each of the amateur bands and covers the range from 1.8 MHz to 30 MHz with four plug in BPF moducles supplied in the kit. 6m operation has also recently been confirmed.

      For pricing see KB9YIG.com (prices have been historically in the $45 to $65 range, depending upon options).

      The v9.0 kit available with the following two options:

      • Current configuration with the four plug in BPF modules
      • V9.0 board kit plus the electronically switched HF BPF kit. Band coverage is from 1.8 MHz through 30 MHz or from 3.5 MHz through 30 MHz plus 6m. The kit builder selects the band coverage at the time of building the BPF kit. (The current plug in BPF modules would not be included with this kit option.)
      • Note: Starting with v9.0 kits shipped after 14 Feb 2009, the USB interface microprocessor will be an ATTiny85 device with Jan G0BBL's new enhanced features code. If there is interest in a programmed ATTiny85 device for an existing v9.0 receiver please let Tony Parks know and he will price the replacement device to cover device cost, PayPal loss and mailing cost.

      For details, see the Softrock Xtall + Lite V9.0 Home page.

    • V9.0 Add-Ons

      • HF-BPF Electronically Switchable 4 Band BPF Board

        For pricing see KB9YIG.com (prices have been historically in the $15 to $20 range).

        Newly in production is a multiband bandpass filter plug-in for the V9.0 RX. This kit provides four switchable BPFs on a single board (as opposed to the four separate boards in the original V9.0 design). In its initial design, switching is manual; however, firmware is currently being updated to allow for automatic switching via the V9.0 RX's USB interface. The kit will ship with parts to allow two different options to be built:

      • 6m/4m/2m VHF Converter Kit

        Another recent addition to the V9.0 Receiver is the 6m/2m (adaptable as well to 4m) VHF conversion board that can plug into the V9.0 board in lieu of the HF-BPF 4 Band Board. This kit, designed by the legendary Jan G0BBL, allow the user to receive in the VHF bands, tunable using the Si570 on board the V9.0 RX.

        The kit ships with all the parts necessary to configure it to receive in the 2m or in the 6m band. As a bonus, these parts also support building it to receive in the 4m band (except for two ceramic capacitors, which the builder would have to obtain).

        Prices are in the $18-$20 range, depending upon whether one needs to purchase a new microntroller chip for the V9.0 RX (Fred PE0FKO has updated the firmware for the V9.0 to support the VHF add-on; older V9.0 boards may require a replacement microcontroller with Fred's updated firmware).

        The Beta Builder's Notes and some discussion of the Theory of Operation are available at the 6m/2m Enhanced Builders' Notes Page.

  • SR Lite V6.2. - Monoband (retired)

     A single band receiver. These pages document the construction of the 40m receiver with a crystal-controlled center frequency of 7.056 MHz. Using a soundcard with a sampling rate of 96 kHz, this RX provides a bandwidth of 7.008 - 7.104 MHz. This receiver was very close to retirement and then Tony (Softrock40 Yahoo Group message 25109) refreshed his stocks at the same prices as before (160m, 80m, or 40m kit - $10 US/Canada and $11 for DX; upgraded 30m, 20m, or 15m kit - $12 US/Canada and $13 for DX) For details see the Softrock Lite v6.2 40m home page

  • Xtall+Lite V8.3 (Retired)

    This is a multi-band receiver. The web site documents the construction of this receiver with a center frequency that is switch-selectable from among 16 pre-programmed center frequencies, giving a band coverage of 160 - 10 m. The receiver uses four pluggable bandpass filter (BPF) boards to handle that band coverage. For details see the Softrock Xtall+Lite v8.3 home page.

    Note: This kit has been retired.

  • Transceivers

    • Softrock RXTX + Xtall V6.3. - Multiband (revived fom retirement)

      For pricing see KB9YIG.com (prices have been historically in the $50 to $130 range).

      This kit was made available for ordering after 14 Feb 2009. This multi-band transceiver is the latest in the RXTX line and, like its single-band predecessor, builds a transmit capability on top of the base multi-band rexeiver's platform.

      Like the RX V8.3, the RXTXv6.3 transceiver board includes a Lite+Xtall receiver function along with the RXTX transmit function. A four-position DIP switch at the edge of the circuit board provides for setting sixteen possible center frequencies for receive and transmit functions.

      The individual Lite+Xtall BPFs that come with the kit are used with the receiver function for band changing and a (separately ordered, band-specific) PA/Filter module plugs on top of the RXTX board for changing the transmit band. As with receive, four PA/Filter modules will be required to cover all HF ham bands.

      Thus, a minimal RXTX for one of the four bands (160m, 80/40m, 30/20/17m, or 15/12/10m) would require one of the included BPF boards and one, separately ordered PA/Filter board for the band in question.

      Also included on the RXTX board is the Rocky 3.x serial interface function for control of the PTT input to the board and to provide paddles input to the Rocky SDR program. Alternatively, one can build the USBI2C interface kit to control the transceiver via a USB line instead of via a serial RS232 line.

      The RXTX+Xtall v6.3 base kit contains the RXTX board kit along with the receiver BPF kits for all HF ham bands. This would include the CMOS Si670 device used on the board. The RXTXv6.3 board also provides for use of the LVDS Si570 part.)

      You can order from one to four PA/Filter board kits to provide transmitcapability on up to four major band segments. Additional PA/Filter modules would expand the band coverage such that all HF bands could be covered.

      For details see the Softrock RXTX V6.3 home page.

    • USB I2C Interface Kit

      For pricing see KB9YIG.com (prices have been historically in the $10 to $15 range).

      The USB I2C interface kit provides a means of setting the Si570 device on a v6.3 RXTX+Xtall transceiver to any desired frequency from a USB port.

      Enhanced builders notes for the USB I2C Interface are under development. Tony's documentation to build the kit may be downloaded from files area of the Yahoo Softrock 40 Reflector. You will have to register at the website to download the documents for the kit.

    • Softrock RXTX V6.2 (Retired)

      . This transceiver adds a transmit capability to the base platform of the SR Lite (in fact, the RX section is nearly identical to the SR Lite). The transmittes delivers 1 watt of output into a 50 ohm load. The types of modulation will depend upon the modulation modes which the chosen software program can implement. This transceiver has been retired after a long and successful production run. See the details at the Softrock RXTX V6.2 40/30m home page.

  • Delta 44 Sound Card Interface module

    A small quantity of this kit is still available for sale.

    For pricing see KB9YIG.com (prices have been historically in the $11 to $15 range).

    • View notes for SR Lite V6.2 View Notes for Xtall+Lite V8.3 View notes for Xtall+Lite V9.0 View notes for RXTX V6.2 View Notes for RXTX V6.3 View Notes for HF_BPF MultiBand plugin board