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Gene T

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Gene T last won the day on May 6 2015

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  1. Gene T

    Data capacity & drive type

    Update: The WBT-3000 has about 1 TB of disk space divided into two internal, non-removable drives. As of version 2.6.0.0, external drives can be used to stream to/from over either the eSATA interface or the USB port. The WBT-300x models have USB3 ports; the USB ports on the WBT-200 series are USB2. The WBT-300x models' eSATA interface have SATA III rates. The WBT-2xx eSATA supports SATA II rates. We recently certified the Samsung 850EVO 4TB SSD for use with any WBT model.
  2. Gene T

    Playback without Transmitting Over the Air

    When Block Transmission is enabled (in Settings - System) the Playback function is disabled. To view the file without broadcasting the signal, leave the Block Transmission disabled and terminate the Tx/Rx connector.
  3. Gene T

    Channelization

    That depends on what you mean by "channelization." The term can be interpreted many ways. Can you be more specific?
  4. The WBT uses a direct-conversion downconverter. Tuners with this design may have a DC component that acts as an interfering signal at the center of the band. It is narrow and has very little affect on most modulation types. For CW and other narrow-band modulation types, just tune a little off the carrier center frequency and, as you noted, it works very well.
  5. Gene T

    Tuner bandwidths in v2.4

    There is an analog, low-pass, anti-alias filter (AAF) in the tuner before the ADC. The Nyquist sample rate is a theoretical value that assumes the AAF is a perfect filter (its response falls to the noise floor at the transition point). A filter’s bandwidth is typically specified as the point where the amplitude is 3 dB below the pass-band as it transitions from pass-band to stop-band. It is necessary to oversample relative to the ideal rate and apply a digital filter to diminish the data representing the roll-off near the AAF transition point. (The digital filter doesn’t change the effective sample rate.) The difference between the ideal sample rate and the sample rate depends on the filter’s shape factor and the flatness requirement.
  6. Gene T

    GPIO, 1PPS, and Ref features

    These are interfaces for which hardware has been integrated but require additional firmware implementation to enable them. This capability will be available in a future software release. The GPIO (general-purpose, input-output) interface on the WBT consists of four 5-volt, TTL lines on a 6-pin, RJ12 jack. The signals on the lines are defined by a custom, embedded application as either inputs or outputs to provide an application-specific interface to provide features such as as antenna switching, COR (carrier-operated relay) status, audio squelch, transmitter blanking, or to pass event signals to/from external processes. The WBT REF (reference) connector may be configured as either input or output to synchronize the frequency accuracy of the WBT's internal local oscillator and ADC sample clock with one or more external resources (e.g., other WBT's or test equipment like a signal generator). When the port is configured as an output the connector provides a 2.5 Vpp , 10 MHz sine wave with an optimal load of 50 ohms. The ideal reference input signal is also 2.5 Vpp. The WBT has an extremely accurate oven-controlled, crystal oscillator (OXCO); without conditioning the accuracy is 25 ppb, with GPS conditioning it's 10 ppb. The 1PPS connector (one pulse-per-second) provides a signal used to synchronize events like starting a data stream and things like time-stamp clocks. A 1PPS signal may originate in a GPS receiver and is commonly available from an IRIG receiver. It may be distributed to multiple devices to synchronize a system. When the WBT 1PPS port is configured as an output, the signal is a 3.3V CMOS logic signal that goes high for 200 ms every second. The rising edge indicates a 1PPS clock tick from the internal GPS or a free-running clock. When the ports are configured as outputs, the WBT is the master or source of both the REF and 1PPS signals. When the ports are configured as inputs, the WBT uses the external signals to drive it's LO and ADC sample clock, and to synchronize data stream starts.
  7. Gene T

    Configuration options

    The WBT can be purchased in the following configurations: · One channel: receive & transmit · One channel: playback/transmit · One channel: receive/record · One channel: receive only · Bandwidth, one-channel: 20 to 40 MHz · Two channels: receive & transmit · Two channels: playback/transmit · Two channels: receive/record · Two channels: receive only · Bandwidth, two-channel: 20 to 80 MHz Note: As used here, a channel refers to a wideband RF transceiver.
  8. Gene T

    WBT Screen Shots

    If you place a USB stick in the WBT your screen shots will be placed there. If you do not place an external stick then the images are placed in on the OS medial at /home/wbt/screenshots and can be transferred out of the device by use of the UltraVNC client connection file transfer option. When you use the screen shot camera icon on the WBT the pop up message tells you where the image will be saved. Don't remove the USB thumb drive immediately after the screenshot message appears. It takes about 10 seconds for it to finish writing the file. When it's removed too quickly, the file name will appear on the thumb drive (at the root) but the file size will be zero.
  9. Gene T

    Low Noise Amplifier

    The Special Use input has an additional LNA relative to the "standard" Rx/Tx input. The Special Use input also has a switchable 3Vdc bias supply to power an active antenna or in-line LNA such as may be used at the far end of a cable run.
  10. Gene T

    FFT display on the WBT-200

    The current software (2.3.1.35) provides a RBW that is BW/1024. A bandwidth of 40 MHz will have a display RBW of about 39 kHz. In the next major release the display RBW will be adjustable. What's recorded is complex time data which is unaffected by the RBW setting. Some of a data stream (typically < 1%) is used for a trace display. In general, a data stream from a digital tuner or the data drive is available to an embedded application so we can do whatever is required to generate the display information needed.
  11. Gene T

    Applications

    The WBT is a development platform which provides dual digital tuners, a high-performance recording system, and dual digital transmitters. There are two models, depending on whether your application supports remote operation (rack mount) or operator use (touch screen GUI). Units can be ordered in any subset of the full hardware configuration. It has an open development environment, too, making it an ideal hardware solution for anyone with an application idea looking for the hardware platform to implement it. There are many ways the WBT can be used in commercial applications. If you would like to discuss the details and see a demonstration use the "Contact Us" link at the top of the page.
  12. Gene T

    Sample rate

    The initial sample rate is adjusted, based on tuner settings, to significantly over-sample the input signal. After digital mixing and filtering, the effective sample rate of the data saved to disk is twice the bandwidth selected when the file was collected. The bandwidth and sample rate values are embedded in the QVRT context fields.
  13. Gene T

    Input sensitivity

    First, a disclaimer: There is no standard definition for sensitivity. Generally speaking, sensitivity is the minimum signal level (Smin) that produces an output with a specified signal-to-noise ratio (SNR). The term minimum detectable signal (MDS) is often used for Smin but is different because "detect" can mean "strong enough to demodulate" or strong enough to rise N dB above the noise floor so the measurement results will vary with modulation type. And, since the noise floor depends on the selected bandwidth, sensitivity does, too. The MDS for the WBT is about -130 dBm with BW = 781 kHz on the standard (RX/TX) input.
  14. Gene T

    Resolution bandwidth

    Resolution bandwidth (RBW) is a frequency-domain concept. The WBT records time samples and has a spectral display that serves as a signal monitor. Currently (SW version 2.3.1.35) the RBW of the spectral trace is [selected bandwidth] / 1,024. So for BW = 40 MHz, RBW is about 39 kHz. Variable RBW is a feature on the product road map but it won't affect the recorded data.
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