EXTENDING SOFTROCK40 OTHER QSD AND TAYLOE DETECTOR TO HF MULTIBAND COVERAGE - PDF
Date of Graduation iii . Signal Analyzer and Radiation Pattern Simulator Used in Development. converters are already split into the I and Q components by the Tayloe detector, but for simplicity we will describe them. Frequency response for PSDR Tayloe detector. standard and performs the channel simulation directly in the code with a already receiver knows that all the messages have been sent and that it is now up to date. Results 1 - 16 of (The Tayloe detector receives at all odd harmonics of the local .. I used Multisim 13 Student Version to simulate the part of the Tayloe detector with the D flip . Ledum, Ah! I see now the date with that article you attached.
The phase combiner is designed for the expected driving impedance resistance. The phase accuracy and image rejection achieved by the phase combiner is very sensitive to the actual drive impedance.
It can be seen from the results that a single sideband noise figure of less than 2 dB is achievable using the image balance mixer of FIG.
From the results, it can be seen that halving the switch on-resistance had very little effect on the gain, slightly improved the noise figure, but improved the IIP3 by about 4.
The switch size could be increased significantly further reducing the switch ON-resistance to effect a further improvement in IIP3. Note that although for this case the image rejection decreases to about The degradation in image rejection with increased switch size lower ON resistance is due to a shift in the mixer output impedance which drives the phase combiner.
The degradation could be mitigated by redesigning the phase combiner for the new driving impedance. In Case 3, single sideband noise figure of less than 2 dB can be achieved approximately 3 dB better than non-image balanced. The noise figure improves slightly with increased size of mixer switch FETs. Insertion Loss of approximately 2 dB can be achieved with load resistance around 1K. The power loss increases to approximately 4.
Resistors were added at the output of the buffers to set the driving impedance to the phase splitter, which in this case was designed for an impedance level r0 of Ohms using non-ideal integrated circuit IC inductors and capacitors. This case was run to verify that good image rejection could be achieved over a broad bandwidth and with integrated circuit IC manufacturing tolerances on the phase combiner elements.
In actual implementation, the addition of real buffers would, of course, incur some degradation in power drain, distortion IIP3 and noise figure. With the addition of the buffers, various other types of quadrature phase combiners could be used, since the buffers could be used to provide gain that would take over the noise of a noisy phase combiner.
The buffers were used only in the simulations for Case 4, and were noiseless and distortionless.
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The resistors added at the buffer outputs contributed to the noise figure in the simulations for Case 4. Although a single balanced mixer topology was used for the simulations, the double balanced topology could also be used.
The double balanced configuration generally has advantages in improved cancellation of even order distortion products and improved isolation from the LO to the RF input port. These improvements are highly dependent upon matching of the mixer circuit elements, and are not included in FIG.
Most of the other comparison results shown would result in similar relative conclusions for the double balanced configurations, although the single balanced configurations give about 6 dB greater voltage gain than their respective double balanced configurations if the same source and load impedances and the same switch sizes are used.
The specific design of the IF buffers will impact current drain, noise figure, and IIP3, but good noise figure and IIP3 and low current should be achievable. The buffers would constitute an IF amplifier. LC quadrature combiners with additional sections could be used to extend the bandwidth over which good image suppression can be achieved.
Other types of quadrature combiners could also be used. Those skilled in the art will appreciate that the appropriate ON-state and OFF-state gate to source voltages are dependent upon the specific semiconductor technology used, and that the circuit voltages need to be biased at appropriate DC levels.
Embodiments of the new mixer circuits described above should find application in products with high performance requirements, such as base station receivers or other receivers with very high second order intermodulation intercept point specifications which require heterodyne mixers.
We maybe able to fix the local oscillator but we may discover that our counter and QSD chips have something inside that does not permit to have real quadrature output and same amplitude signals. Faster and more performing chips are showing up but not always in a size manageable for a homebrewer. These aspects force us to compromise as much as possible but, at the same time, trying to get as many benefits as possible too.
Recently I was able to implement and experiment one of my old projects I started on paper at beginning of The project has been adapted to the SoftRock40 Version 6 and it is the multiband Digital Quadrature Generator circuit diagram reported in Figure 1. The complementary LO signals are feeding the two flip-flops forming the real Digital Quadrature Generator in a configuration to divide by 2 the oscillator signal frequency, delivering 4 phases oscillator signal at fundamental frequency.
An external control, employing a multiturns potentiometer, operating as a manual phases or quadrature balance is associated with the Squarer. Be careful not to break these pins.
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This will stop interferences. This transformer is wound on a balun core type or For the SR V6 do 3 windings of 4 turns each, while for SR V7 do 5 windings of 4 turns each. Use any enameled wire size that will permit the windings. Pay attention to the secondary windings phase. The total cost of the TBR turned around euro, accounting also for the components I had in already my junk box or I salvaged from discarded equipment people tend to bring to me mostly the inductors. I purchased most of the regular components in a local shop in Antwerpen Ratothe more exotic components were purchased through Conrad a well known mail order service in Western Europe.
Tests and results so far I am currently performing some intensive testing on the prototype when time permits. These results were obtained using the following configuration: No "birdies" where found on any band when running the TBR with a shorted antenna input, which is a very appreciated characteristic of the direct conversion receivers.
The accuracy and stability of the frequency setting is remarkable thanks to the TCXO, no difference in frequency setting was needed when testing with the crystal controlled rf generator, even not after several weeks. As one can see, there is still an issue with the THD, which is a bit less than 30dB.
I used the RightMark Audio Analyzer 5. This seems to point in the direction of the AGC circuit as the culprit.
Still to be done in near future: Kenwoodso that the Rig Control window of Hamscope can be used. Antenna Confronted with the issue of the antenna, and being aware of the saying that a good antenna is the best HF amplification one can get, I experimented for a while with a random wire antenna running over the garden out of a first floor window.
Later I made an tuned magnetic loop antenna for 20m and 40m from copper tubing, the sensitivity was rather disappointing, but this was maybe due to the fact I used it indoor behind a window that was actually smaller than the loop itself.
I further experimented with offset fed dipoles and end fed dipoles for 20m and 40m out the same first floor window. Since the length of the dipole did not match my garden and had to bend it, it became a crooked end fed dipole.
There are no tall trees in this part of the suburb and an huge antenna mast is a no gothe dipoles were suspended just some m above the lawn, yielding a rather skyward looking radiation pattern that is what is written in the literature. After some more reading I came to the conclusion that a ground plane vertical in the garden would be a good solution, as it would at least yield a low elevation radiation pattern.
As is would be a major project, I wanted the antenna to be multi-band and capable of transmitting, though I would use it for receiving only on the 20m and 40m bands for now.
So, I selected a spot in the garden compromising between the lawn, the shrubs, the neighbours, etc. With the use of the excellent antenna simulation software MMANA I designed something that should yield acceptable results for the bands above 40m. Of course, no use to go on the 80m band or on the m band for that matteras an antenna height of about 7m was the maximum I felt I could go without causing some concerns in the neighbourhood.
Those who want to experiment further, can possibly find some use in GPgarden. A galvanised steel pipe of 25mm diameter and of 2m length was hammered into the soil until only 35cm stood out.
It serves as the mechanical base and as electrical ground for the antenna.
Four radials were made of 7m lengths of 2. They were laid approximately into four quadrants, they had to bend here and there to spare the shrubs and the lawn.
The radials electrically are connected to each other, to the galvanised steel pipe, and of course to the mantle of the feed coax. The radiating element of the antenna itself is made of 4 telescoping Aluminium tubes of 2m length each, their diameters are respectively 25mm, 20mm, 16mm and 13mm. A set of hose clamps of the appropriate diameter are used to clamp the one tube into the other when erecting, care was taken to slid the tubes for a few centimetre with a hand saw.
As about 40cm of each tube remains into the previous, the total length of the radiating element is 6.
The whole construction is freestanding and tops at 7. The weak point is the plastic tube base construction if only I could have found a glass fibre tube of the appropriate dimensions instead of the double layered PVC tube.
Since the radiating element can rapidly be dismounted it weighs less than 2kg this is not really a problem. See here a drawing of the entire construction, see also the pictures in the garden erected and collapsed.
Obviously, this kind of antenna need some impedance matching, I decided rapidly that a remote antenna tuner placed on the radiating element would be best, especially since I needed some 40m of coax from the antenna base to the receiver. MMANA gives a good indication of the impedances at the various frequencies see spreadsheetwhich determines the design of the antenna tuner.
The latter consists of a high pass L-C arrangement made of a heavy-duty coil put in parallel with the antenna and a variable air capacitor that is put in series with the feed.
EXTENDING SOFTROCK40 OTHER QSD AND TAYLOE DETECTOR TO HF MULTIBAND COVERAGE
The coil is made with 2. Tiny wood strips were epoxied to the turns for additional stiffness. The coil is tapped at 2, 3, 4, 5, 6, 8, 10, 12 and 14 turns, its inductance can be adjusted rather coarsely from 0.
The selection of the taps is made by a heavy-duty ceramic rotary switch the indexing mechanism was removed. Two heavy duty DPDT relays where foreseen in order to be able to change the topology of the tuner. A pF in series with the antenna is needed according to TLW for a correct tuning in the 30m band. The relays are not used for now as the TBR does not receive in this band. I used a pair of radio control servos that I still had in my junk box to rotate both the variable capacitor and the rotary switch.
These little devices are used for model airplanes etc. The particular servos I used were the JRC type and when fed with 5V and controlled with a width modulated pulse between 0. To control all this remotely, I build a simple device consisting of a micro controller again the AT90S and a few power transistors see the schematics and the firmware source.
It accepts a few simple commands through the UART and position the servos and relays accordingly, see here its picture. The power up to 0. The whole is fed near the receiver with 12V DC, the control signals are nothing more than polarity reversals following at baud the TD line from the COM port of the PC see the schematics. A small circuit was build for that purpose, as was the small GUI see the screenshot and the zipped source with a few simple controls written again in VB6see also its picture.
To avoid of a possible source of interference near the antenna, the microcontroller is put in sleep mode including its crystal oscillator when not in use, it has to be woken up with a break signal of 50ms on the COM port prior to each command.