LD-1C Enhanced SDR
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Following the LD-1B and the improved LD-1B2, the LD-1C enhanced software-defined receiver takes it to the next level. It has all the features of the LD-1B2, plus enhanced sensitivity thanks to two stages of RF gain. Additionally, it has a diode-protected RF input to guard against damage from static discharge and from switching mishaps when using it with an external transmitter or transceiver. When equipped with an internal transmitter module (LD-1TX) its internal RF sampler can “loop back” the transmitter output (greatly attenuated, of course) to the receiver input for monitoring and adjustment.The LD-1C can easily be upgraded by installing an LD-1TX 5-Watt transmitter module. An LD-1C thus upgraded is identical to an LD-1TR software-defined transceiver. The installation requires no tools except a small Phillips screwdriver and takes less than five minutes. | ||
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Like all Lazy Dog Engineering receivers, the internal firmware can be updated when necessary by the owner. No special equipment is necessary, because firmware updates load throught the USB port using the included bootloader.The LD-1C works seamlessly with HDSDR, Winrad, and SDR# (SDR-Sharp) via an included ExtIO dll, which is automatically installed by the included installer application. The included CD contains the installer, a copy of the firmware, a detailed and illustrated User’s Guide, and a schematic.
Like all Lazy Dog products, the LD-1C was designed and is manufactured by Lazy Dog Engineering LLC, right here in the Garage Shoppe. Like its predecessor, the LD-1B’s design was influenced by KB9YIG’s excellent “Softrock-40″ series of simple SDRs. After building a crystal-controlled Softrock for 20 meters, I was very impressed by its performance. While I didn’t (and still don’t) have the equipment to make exhaustive performance measurements, it seemed just as good as my FT-817 at a fraction of the cost. The only problem was its frequency coverage. I could receive anything within 48 kHz above or below the fixed LO frequency of 14.060 MHz. I set out to create a general coverage version, covering 500 kHz – 30 MHz, with plans for an add-in transmitter module. |
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The result was the LD-1A, which is similar in concept to the Softrock 40 version 5, but with a DDS local oscillator which extended frequency coverage down to 500 kHz. The LD-1B extended it further, down to 200 kHz, with the addition of three more preselector filters. The LD-1B2 improved the noise floor with an isolated USB connection and a buffer amplifier ahead of the QST. The LD-1C takes it a step further with two stages of RF gain, plus an RF sampler and diode protection.The LD-1C has much in common with earlier Lazy Dog receivers. The I/Q local oscillator is generated by a pair of Analog Devices AD9834 DDS chips which, which are always set to the same frequency but with a 90-degree phase shift between them. The eight preselector filters electronically switched. A Silicon Laboratories microcontroller selects the preselector filter and controls the DDS chips, as well as providing a USB port so the whole thing can be controlled from a PC. | ||
LD-1C & HDSDR Receiving PSK-31 |
The LD-1C has all connectors on the rear panel, with the front panel reserved for the power switch and indicator LED’s. In other words, you can set it on the desk with all the cables out of sight, just as you would do with a “conventional” radio.The PCB slides into slots in the sides of the enclosure. The connectors, indicator LEDs and power switch are mounted directly on the PCB, with NO wires to come loose or become intermittent! The PCB is exactly the length of the enclosure, so to disassemble it you just remove the screws from one or both panels, remove the panel(s), and slide the PCB out. |
You can order an LD-1C from Lazy Dog Engineering
I haven’t been able to put together detailed performance measurements, but here are the specifications I can provide:
| FrequencyCoverage: | 100 kHz – 30 MHz | ||
| Sensitivity: | Better than 0.18 microvolt for 10 dB SNR at 10 MHz | ||
| Image rejection : | Comparable to Amateur-grade receivers | ||
| Overload Characteristics: | Comparable to Amateur-grade receivers | ||
| Power Supply: | 6 – 14 VDC “wall-wart” with 2.1 mm x 5.5 mm male connector, available seperately | ||
| Front Panel: | Power switch (pushbutton, push-on, push-off), green power indicator LED, red mute indicator LED. | ||
| Rear connectors: | 3.5 mm stereo output jack, 3.5 mm stereo input jack (for planned transmitter module when available), 3.5 mm “stereo” accessory jack, USB mini-B for connection to host, SMA female antenna connector, and 2.1 mm x 5.5 mm coaxial female power connector (center positive). | ||
| Dimensions: | 1.1875 x 3.125 x 7.0 HWD (overall) |
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