#BE FS30 FM STEREO GENERATOR GENERATOR#
So, U1A is a comparator that, when the ramp waveform reaches a certain threshold (set by R2), stalls the ramp generator just enough to increase the intensity at that point. I wanted to be able to indicate, on the screen of the scope, where 10.7 MHz would be on the X-axis, and came up with the rather crude but effective thought that, if I paused the timebase for just a couple milliseconds at any given point, it would light the screen phosphors a little brighter than the others - in other words, create a "blip" on the screen. This block accomplishes the tasks necessary to receive FM stereo: Separation and demodulation of the L + R and L - R signals and then demultiplexing to separate. Figure 9 depicts the GRC flowgraph for a basic FM stereophonic receiver that uses the WBFM Receive PLL block. But, my sweep generator was old, large and kind of a pain to use, so I built a small, stripped-down unit that didnt take up more bench space than. Receiving FM stereo is the next stop on our tour of the FM broadcast band. The circuitry around U1A, Q1 and Q2 is, I think, kind of cute. Yeah, its possible to align by ear, but I find it actually faster and easier to align the IF and discriminator stages with a sweep generator, RF probe and scope. The 555 Timer is configured as a sawtooth-wave generator that serves as a common timebase for the VCO and "X" axis of an oscilloscope (via buffer U1B) the gain of U1C determines the sweep width, or differential between the high and low frequencies of the generator, and U1D adds a bias voltage to the ramp to scale the signal to tune the oscillator as desired. The heart of the circuit is a voltage-controlled-oscillator (VCO) based around Q4, that, at the center of it's control voltage range, runs at 10.7 MHz. The 1000A was quickly followed by the model 1700A which was a state of the art audio measuring system which could read distortion (THD) down to 0.001 and whose. We bought a load of these instruments to use in the factory and also became the UK distributors of the product line. There are some great YouTube videos demonstrating the procedure, so rather than go into the procedure here, I'll focus on the circuit I threw together. The first product was the model 1000A FM Stereo Alignment Generator. The FX-50/E accepts multiple wideband composite inputs from a stereo generator or SCA. When used in conjunction with an oscilloscope and detector probe, it allows one to view the shape, or bandpass, of a tuned circuit. within the 87 to 109 MHz FM broadcast band in 10 kHz increments. A Stereo Generator will have a BNC output, which can be connected directly into your Exciter. This contains the L+R (Mono), L-R, and 19Khz Stereo Pilot Tone. 4,737,725.For those who may be new to the hobby, a sweep generator is an oscillator that repeatedly "drifts" from one frequency to another over a certain period of time, then abruptly "tunes" back to the frequency where it started. A FM Stereo Generator takes a stereo audio signal, and converts it into the FM Baseband format. Low-pass filter overshoot compensation circuitry employed in the Model 715 is protected under U.S. Digital Synthesis Sampling RateĦ08kHz (16X subcarrier oversampling) Power Requirementsġ05-130VAC or 210-255VAC, 50/60Hz 15W Size and Weightġ- 3/4” H x 19” W x 7” D (1U) 7 lbs. TTL-level symmetrical squareware, in phase with 19kHz Stereo Pilot component in Composite Output signal. Level is adjustable between -5dBu and +12dBu (0.5 to 3V r.m.s. Single-ended (unbalanced), “zero” (voltage source) impedance. “Safety” clipping of the Composite Output signal is performed prior ro Stereo Pilot insertion.
Program signal clipping is relegated to non-repetitive limiter overshoots 1 ms or less in duration. DENSITY control alters time constants and platform values. A high sensitivity VU meter allows accurate measurement of audio input levels. Its stereo separation performance is higher than 60 dB with S/N higher than 85 dB.
This is a high performance Stereo Generator and 2 band automatic Audio Processor built into a one- rack space unit. limiter action and compressor gain state. NSC1 Stereo Coder and 2 Band Audio Processor. This device is a FM signal generator covering 88 to 108 MHz with an output attenuator calibrated from 0.5 uV to 30 mV into 50 ohms.It modulates the FM signal with a composite stereo signal for aligning stereo decoders. I purchased this at a hamfest (amateur radio convention).
Independent high frequency limiter conforms to selected preemphasis characteristic. FM Alignment Generator This is a FM tuner alignment generator. Slow (0.5dB/sec.) correction for long term input level variations ☑0dB capture range displayed by LED indicators.įast-acting peak limiter has secondary “platform” time constant to compress dynamic range with average-value weighting. Stereo Separationħ5µs or 50µs characteristic.TEST INPUTS bypass processing and give a “flat” output. (through appropriate deemphasis network) ☑dB, 20 Hz - 16kHz -60dB or better at 19kHz.