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The LD-1B2 features a USB isolator, which improves the noise floor (and sensitivity) by about 6 dB compared to the original LD-1B! Other design changes yield an additional 6 dB improvement. The LD-1B was a great Software-Defined Radio (SDR) before, and is now literally FOUR TIMES as good! It's a general-coverage, 100 kHz - 30 MHz, USB-controlled receiver intended for Radio Amateurs. Its low cost and high performance (comparable to a typical Amateur-grade receiver, such as an FT-817) make it a great addition to any ham shack. Small in size, it is also ideal for portable operation using a notebook computer. It does require a host computer, either desktop or notebook (or even a netbook) with Windows XP, Vista, or Windows 7; a souncard with a stereo line-in connector; and SDR signal-processing software (Winrad is recommended, download it at no cost). The current host software and firmware may be downloaded on the Downloads page. "Wav" format demonstration files, recorded using Winrad, are also available on the Downloads page. These may be played back using Winrad, and will let you experience the LD-1 before you buy. The LD-1B2 has a very nice extruded aluminum enclosure with an attractive black anodized finish. Licensed Radio Amateurs may upgrade any LD-1B or LD-1B2 receiver by adding an LD-1TX transmitter module, or may order the LD-1TR 5-Watt transceiver which is an LD-1B2 with an LD-1TX installed. |
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LD-1B Hardware: The LD-1B bandpass filters the RF input, then downconverts it using a quadrature local oscillator (LO) and mixer. The output of the quadrature LO / mixer is a pair of intermediate-frequency (IF) signals, one of which is called the in-phase (I) signal and the other is called the quadrature (Q) signal. The I and Q signals, are conditioned by a simple lowpass filter, then send to the left (L) and right (R) channels of the soundcard's line-in connector. Addition of a 5 Watt transmitter module (being developed) is provided for with PCB headers, Line-In and Accessory connectors, and an antenna relay. Installation will not require any cutting, drilling, soldering, etc. An external "mute" or "transmit" switch may be connected via the Accessory connector. (Back to Top) |
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Host Software: The host's SDR software, which is available from several third-parties at no cost, performs IF signal processing and demodulation. Compatible modes include AM, FM, SSB, CW, and in some cases DRM. "Soundcard" modes such as PSK31 are available using appropriate software and a second soundcard or Virtual Audio Cable. Winrad is preferred, because the LD-1A software installation package includes a DLL which connects it with Winrad's controls so the operator can change the LO frequency either from Winrad or from the LD-1 control panel. A standalone LD-1B control application is also included in the installation package to let you use your LD-1B with other SDR software, such as Rocky. (Back to Top) |
| USB-Controlled Frequency-Agility: The SDR software has a tuning range of 48 kHz, 96 kHz or 192 kHz, depending on the soundcard's sample rate. The tuning range is centered at the LO frequency, so the crystal-controlled LO found in many low-cost SDR's restricts the frequency coverage to a single 96-kHz range. The LD-1B uses a synchronized pair of direct digital synthesizer (DDS) chips as its quadrature LO, resulting in extreme frequency agility. The LO frequency is selected via a USB connection, either from the LD-1B's control panel (shown above) or directly from Winrad. When the LO frequency is changed, one of the five preselector filters is automatically selected. These control functions are performed by a microcontroller. The microcontroller's firmware may be updated by the user via the USB cable. (Back to Top) | |
| Soundcard Considerations: Like any SDR which relys on a host computer and soundcard, the LD-1's performance is dependent on the performance of the soundcard. An expensive professional-grade soundcard like the Delta-44 is NOT required. The LD-1B performs very well with a Creative SB1090 USB sound adapter, which is available for $50 - $75 dollars and is ideal for portable use with a notebook PC. IMPORTANT: Most notebook PC's have a two-channel (stereo) audio output, but only a single-channel (monaural) mic input. This is not adequate for use with an SDR like the LD-1A, so if you plan to use a notebook as a host you MUST use a good-quality USB sound adapter like the Creative SB1090. When selecting a USB sound adapter, make sure it has a stereo line-in jack. Cheap ones and "dongle"-style adapters general have only a mono input. (Back to Top) |
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| Performance: The LD-1B's performance has not been fully characterized, but after using the prototype for several months with an MFJ Super High-Q loop antenna, an SB1090 sound adapter, and Winrad, it can be described as comparable to the performance of Yaesu FT-817 in terms of sensitivity and out-of-band signal rejection. In terms of usability, it is far superior. The SDR software provides a spectrum-analyzer-like graphical display of all signals within the tuning range, and the operator can instanly tune to any signal with a single mouse click. The IF bandwidth is highly adjustable, as are the AGC characteristics. After operating the LD-1B with Winrad, going back to a non-SDR receiver feels like flying blind. (Back to Top) | |
| Professionally Designed For Amateurs: The LD-1B was designed by a lifelong ham with degrees in Electrical Engineering from Rose-Hulman Institute of Technology and Purdue University, and 30+ years of industrial and academic experience, so you can rely on its technical soundness. It is built on a high-quality PC board using dedicated power and ground planes as well as extensive decoupling to minimize EMI and EMC problems. (Back to Top) | |
| Frequency Coverage: | 100 kHz - 30 MHz |
| Sensitivity: | 0.18 µV for 10 dB signal-to-noise ratio 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 |
| Rear Panel: | 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). |
| Front Panel: | Power switch (push-on, push off), green LED power indicator, red LED mute / transmit indicator |
| Dimensions: | 1.1875 x 3.125 x 7.0 HWD (overall) |
