As the reference-frequency oscillator of frequency synthesizer are operationally set crystal-controlled oscillators to the frequency 100 MHz. One-watt version is done without soldering the components of 30 W amplifier. 15 V.įigure 2 – Printed circuit board of transceiver SunSDR 15M as a set The first chain is done on the operational amplifier OPA2674, in the second chain – two transistors RD16HHF-101 (pull-push curcuit in class “B”). Amplifier is built on two-circuit scheme and has the amplification of the order 40 dB. The main peculiarity of SunSDR 15M from the previous version is the embedded to the board power amplifier 30 W. Two modifications of the device were developed - SunSDR M and SunSDR 15M.
Receiver’s measurements with the soundcard M-AUDIO – Audiophile 192 are shown in tables at the tab Characteristics. Each gain level defines receiver’s sensitivity. Receiver has 5 gain levels, which are switched from the program ExpertSDR. Using such technology allows to make lower the level of intermodulation distortion transceiving tract and makes higher a receiving dynamic range. Band LPFs (low-pass filter) are executed on a ceramic chip coils. It should be also noted a low level of the carrier frequency transmitter (lower than -55 dB), reached by right component layout of mixer and transmitting tract topology. Therefore it makes lower the level of noise pickups from digital chains (because now they are placed inside CPLD crystal). The amount of digital lines on a PCB were reduced because of mounting on the card CPLD. Due to this engineering solution the device has certain advantages: more reliability, small enclosure dimensions and weight. SunSDR electronic part is executed on one two-layer PCB. High-speed USB 2.0 interface is used for transceiver’s control. Mounted Jack 6,3 mm connectors possess qualitative electric contact, a factor which makes lower quadrature disbalance. This device has a built-in protection from polarity reversal. Anodic robust aluminum box doesn’t conduct electricity, which prevents from possible shorts if bared wire hits the case. SunSDR is a PC device, which in connection with SDR program represents the full value transceiver. Small number of the components reduces the level of noise floor. It is also possible to record the signal from the air and to reproduce it into the air back. This device opens up absolutely new opportunities for the users, because it’s possible now, not only to hear the signals from the stations, but also to see them on a screen of the SDR-program. Transceiver is intended to the concerned work with PC and sound card.
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