The following six documents cover a range of topics that may be of interest to Optoelectronics Inc. customers. Contents: Document 1 Computer Interface Adapters for Radios Document 2 Towers and the Scout Document 3 Using the Optoelectronics N100 with Scanners and Receivers Document 4 Scout Timebase Accuracy Discussion Document 5 What the Scout will Count - User Expectations and Reality Document 6 Product Price List (included for reference only, check with the factory for current pricing) ***************************************************************************** Document 1 Computer Interface Adapters for Radios Everything You Need to Know About the CX12 and then Some! Why are they Needed? The need for an interface is caused by the way in which data has to move in and out of a PC. If you don't use the key board and you don't put a custom board inside of the computer then you have to use the serial interface (computers will typically have two with the mouse using one) or the parallel printer port. The Problem With Com (Serial Interface or asynchronous communications) Ports The serial or com port uses electrical signals to indicate a zero or a one for logic levels. A logical one can range from positive 3 to positive 15 volts and a zero can range from negative 3 to negative 15 volts. Radios, DC440s and Scouts use microprocessors that can only generate positive voltages and so can not directly interface to the computer serial port. RS-232C, the Standard Because this is a common problem for many devices that must connect to a computer, Maxim (a semiconductor manufacturer) produced a chip that makes its own positive and negative voltages and converts the microprocessor's logic levels (called TTL for transistor transistor logic) to the RS-232C standard. This chip was initially a $5 part. Market place pressures and competition from Harris and others has brought the price down. CI-V (Communications Interface number 5) You would think that everyone would simply put this chip inside their radios and be done with it. In fact the AOR AR300 and AR2500 have the MAX232 chip (or something like it) inside. A new problem arises in that you can't put more than one device on the serial port at the same time. ICOM came up with a neat work around for this problem with their CI-V interface system. Any number of devices can be placed on the CI-V (stands for Communications Interface number five)bus as long as each one has a unique address. Therefore a command sent down the bus will be obeyed only by the device whose address precedes the command. Everyone Can be on the Same Line It is exactly like the old party line system used for telephones up through the 1950s. The difference is that everyone is on the line at the same time. There are rules that keep the communication from getting out of hand. If two people try and talk at the same time, they both stop and wait for a period of time and try to talk again. This works because everyone waits a slightly different amount of time before talking. Only when there is no data on the line can someone start talking. CI-V is slow but if you don't need fast then there is power in this interface because many devices can be on the same line. Why Didn't Opto always use CI-V Because we didn't need to communicate with other devices such as radios. We initially developed our own full duplex system (which is actually better in many ways, especially speed, but it does not allow for multiple devices on the same line). Full Duplex means that you can talk and listen at the same time over two separate lines. The original CX12 was Full Duplex only and it was only about a year ago that we added the switch that shifts the CX12 to CI-V. The switch simply shorts the talk and listen lines together when moved to the CI-V position. OptoScan Development, Picking the best interface. The fastest way to get the OptoScan 456 to market was to have it respond to ICOM like commands over the CX12 interface. The Scout was then made CI-V so that we could have Reaction Tune to the OS456. The older 3000A and M1 were then Full Duplex with the Scout and OS456 CI-V. The OS456 has the equivalent of a CX12 built inside. You can even use it when you are not running scanning software. You can use it to download frequencies from the Scout. Some customers have added a DC440 to their OS456 so they can get Tone and Code data when they are under local control (the Radio Shack Micro controlling the radio not the OS456). For this reason, the CX12 is not an accessory for the OS46. As we put new instruments on the CI-V interface we make use of ICOM commands where ever possible but create new ones to cover unique functions. In addition, we have new address defaults reserved for our own instruments. We document these additions to the basic CI-V instruction set (document is available from ICOM). The DC440 Interface Changes to CI-V The DC440 started out life as Full Duplex. This was an advantage because you could communicate with it and in fact computer control it using a modem program transmitting ASCII text words (Asynchronous Synchronous Computer Interface). The difficulty was that for Computer Controlled Scanning, you needed a separate computer serial port for the radio and one for the DC440. Almost no one has two available serial ports on their computer. (the Mouse usually takes up one.) This limited DC440. We decided that it would be more useful to more people if we converted to CI-V. We now have ScanStar and ScanCat support with RCSI working on it. The DC440 is now perfect for ICOM owners who want decoding capability for their radios. CX12 and CT17 Not Usable With Scanning Software The next problem occurred when using an interface with scanning software to to control an ICOM R7000. It doesn't work directly out of the box. The problem was that this particular radio can not scan unless you run a squelch status line to the computer. The command set for the 7000 does not include an instruction to tell the computer that squelch is open. This means that the computer can not tell when the radio is receiving something. The squelch status tells the computer when the radio finds a signal. Squelch status is improvised by using the Recorder Remote Jack on the back of the radio. This is actually a relay that is slow itself and ScanStar advises its replacement. ScanCat uses the relay. For the fastest possible scanning, the squelch status line should be routed outside the regular data stream (the CI-V is slow). The customer needed to connect to the recorder remote jack and run this line into the PC. This has been troublesome for the customer who then needed to lash up a strange cable configuration and solder it together. AOR, AR8000 Uses Separate Squelch Status Line The AR8K must use a separate squelch status line to achieve a 20+ channel per second scan rate. If you don't use it you will only get about 10 channels per second. It became clear to us that in order to provide for both the R7000 and AR8K along with any future radios (all radios scan faster with a separate squelch status line into the computer), we should provide a dedicated squelch status input. The CX12AR is the only general purpose converter with a dedicated squelch status input. Computer Controlled Relay Closure for Tape or Other Use The CX12AR is using a line out from the computer (pin 20) called DTR which stands for Data Terminal Ready. It is unused normally. The software gets to control a relay that can be used to control a tape recorder (remember that with an R7000, the Radio's Recorder Remote Jack is already being used). CX12 and the AR8000/2700 The CX12 has full duplex capability and so could always be used with the AR8000/2700 series radios. Even the original models without the switch inside. The only thing we have added is the dedicated squelch status input and an adapter that will plug into the radio. AR8000/2700 Interface The AR8000 hand held needs at least five connections, Data Send, Data Receive, Squelch Status, Power and Ground. Power is not really needed but they use it to power their interface. With that many connections they should have used a mini Din connector but chose FFC (Flat Flexible Cable). The cable is not generally available in the US, it is relatively expensive, and the connector used in the radio loosens up very quickly. Any cable movement is liable to disconnect the data. The AR2700 is worse because it needs an additional adapter to get to FFC! We plan to figure out the best way to add hardware jacks to the radio and get acceptance from the other manufacturers and from the hobbyists. This will make it easier for the Scout and R50 to connect to the AR radios. CI-V for Everyone The best solution is to make a translator that will adapt CI-V commands to AOR commands (three very different sets of commands for 2500, 3000, and 8000/2700). This device will enable older Scouts to Reaction Tune the AR8K and scanning software to multiple scan the radios. It is interesting to note that the CI-V interface is being used by other radio manufacturers, it is referred to as IC751 emulation. Our NUDEM, when it comes out, will be CI-V and will be able to work with any Radio on the interface. Direct Comparison of CX12AR to other Popular Units Model CX12AR CT17 EDCO* AOR JCom* Feature CI-V & Full Duplex yes no no no no CI-V yes yes no no yes Full Duplex yes no yes yes yes Tape Out yes no no no no Squelch Stat. yes no yes no no AR8K support yes no yes yes no Price $99 $110 $105 $150 $49 * Requires tha DTR line to be high via software control. The Significance of the DTR Line The EDCO and JCom (Ramsey) adapters do not use power supplies but sneak a little current from the computer. The software must cooperate and keep the DTR line (pin 20 on a DB25 and pin 4 on a DB9) high or there will not be any power. For instance, thed current Scout download utility will not work with the JCom adapter because it ignores the DTR line. We have also dedicated the DTR line for the tape relay control output from the PC. This means that the software guys must support the CX12 and JCom/EDCO at the same time! ============================================================================== ****************************************************************************** Document 2 Subj: Towers and The Scout From: Jeff Matheson (from Compuserve HamNet with permission) With a Scout in hand it is pretty hard to resist the urge to check out that big orange (red if you will) and white metal shrine of communications just down the road from you. Isn't it? Bill Owen discussed tower space and we really need to touch on a few key areas regarding towers, so here we go... a non-technical, simple and hopefully informative set of tid-bits! Over the last decade we have seen a trend getting away from the towers being service oriented. A tower at a police station which once held a stick or two for police and fire department communications NOW could have 5,10,15 sticks on it for Public Safety, Cellular, Business, Paging etc! Cellular and cable TV towers are host to Public Safety as well, now more than ever. Tower space is sold, leased and swapped on a regular basis. As Bill also mentioned, with various users sharing a common tower, simultaneous transmissions from two or more transmitters can generate some very odd frequency readings on your Scout or frequency counter. It is important to note that visiting your favorite tower site during peak hours might not always be the best idea. Sure you will get alot of readings but a good portion of them may be useless. A better tip would be that of packing a picnic lunch and heading out mid-day on a week day (if time permits). Sunday afternoons are good, but remember that many businesses are closed on Sundays and you could miss those captures. 5 minutes is not long enough! You really need to approach this project with dedication and gather enough data to arrive at some degree of solid and useful information. Anything less and you will find yourself disappointed! Radio transmitters sites are not always located at radio towers. You might want to take a closer look at some of those water towers in town. Multiple story buildings are also prime locations for antennas. It doesn't have to be a sky scraper. A two story building with good ground elevation can also be a piece to your puzzle. And since we are on the subject.. I'll bet you thought that antenna high atop that bridge belonged to the "Port Authority" or "Joint Bridge Commission" eh? Pay attention to the antennas in use at the site of your choice! NOT ALL antennas are used. It's cheaper to leave the antenna and cable there for future use than it is to remove it. ============================================================================== ****************************************************************************** Document 3 Using the Optoelectronics N100 with Scanners and Receivers In response to customer requests, Optoelectronics has developed the N-100 notch filter for use with frequency counters to eliminate FM broadcast signals. It is called a notch filter since when looking at a plot of attenuation versus frequency, the filter appears as a deep notch over 88 to 108 MHz, passing all signals except those within that narrow range. While this filter, the N100, was designed for use with frequency counters to eliminate spurious counting from strong local FM stations, in practice it finds wide application with other radio equipment. In the past, most broadcast stations were placed outside of urban areas, where land was inexpensive. Broadcast interference was uncommon since few people lived near high power broadcast stations. As populations expand, it has become common to find broadcast towers located near suburban neighborhoods. Putting a 100 kilowatt transmitter within a thousand feet of a TV set or scanner can have some unfortunate effects on the receiver. Signal levels far in excess of those anticipated by the radioÕs designers are present at the antenna terminals and tend to overdrive and saturate all but the most robust units. Even if recognizable music is not heard as interference, intermodulation and desensitization may be present and reducing the affected receivers usable sensitivity. Wideband FM broadcast signals, especially in the case of their harmonics or intermodulation products, may not be appear to be music but rather a choppy intermittent interference. Desensitization by the sheer amplitude of the FM broadcast signal may just reduce the receiver front end gain with little other evidence of overload and make the reception of weak signals impossible. In all of these cases, there are only two solutions available - a better receiver or less FM broadcast signal. Owners of modern triple conversion (up conversion) scanners already have an advantage here since they are more resistant to this interference, but not immune. A directional antenna can null the FM broadcast signal but only at the expense of not receiving anything in that direction, as well as requiring an antenna rotator. Another way of reducing the signal is often the best solution: an FM notch filter. This filter reduces the strength of 88 - 108 MHz FM broadcast signals by a factor of over 1000 (30 dB) while leaving the remainder of the spectrum unchanged. Simply inserting the N-100 between the antenna and receiver will reduce FM broadcast interference and allow modern receivers to reach their full performance. ============================================================================== ****************************************************************************** Document 4 Scout Timebase Accuracy Discussion First, lets talk about the accuracy required for the task at hand. Everyone would like to believe that whatever transmitter or frequency counter they happen to have in their hand is absolutely correct - unfortunately that's not so. As long as the signal being received by the scanner is contained in the IF of the unit, little harm is done if the signal is not centered. A signal 5 kHz off will probably sound distorted but still be readable. The PRO-2006 uses a TEW TX1824G TCXO for it's reference oscillator, which is spec'd at +/- 3 PPM over 0-50 degC. At 900 MHz, this is 2700 Hz off, not counting the drift of the 3rd local oscillator. A Motorola UHF radio manual states its stability at 5 PPM. The Scout time base is about the same accuracy or better, although over a smaller temperature range. No large effort was made to put a high stability time base in the Scout not only because there was no room for it and it would increase the cost, but most importantly, it doesn't need it. The Scout is the first Opto product designed not to measure a frequency, but to identify the frequency in use. Accuracy is only required to identify the nearest 12.5 or 25 (or 30) kHz channel being monitored. Complicating this is the fact that the Scout uses a very fast gate time that is subject to seeing the low frequency FM on signals, especially in the case of broadcast FM stations. Slowing the gate bogs down the filter function making the capture too slow. Slower counters average out the modulation over many cycles of the modulating audio. The point of all of this that the accuracy of the Scout (when properly calibrated) is sufficient for the job it is intended for. Secondly, let's discuss the best way to calibrate the unit. I have read at a suggestion to put the Scout (or any other counter) into the longest gate time possible, count a known frequency from a transmitter, and adjust the counter for the right reading. There are a couple of things that could be clarified in this procedure. Consider the accuracy of the source to be calibrated against. A Kenwood UHF base station I have is rated at +/- 3 PPM, hardly a reference standard. A Kenwood TH-77 HT gives no accuracy spec at all. Generally, it is a good rule of thumb that the calibrations standard must be 10 times as good as the unit to be calibrated, here requiring .1 PPM. While a typical high grade VHF or UHF transceiver can be expected to be close to frequency, at BEST they are barely up to the task of this calibration. And forget using a 49 MHz phone. Probably the optimal solution is a two way radio shop's frequency standard. Also don't be tempted to recalibrate the unit if you occasionally get readings a little off from what you expect. Maybe the source is off frequency! There is also no need to use extremely long gate times to accomplish this calibration. To get 1 PPM resolution (+/- 1 count) requires letting the counter accumulate 1,000,000 counts. Since the Scout uses a divide-by-64 prescaler (more recent units a divide-by-8), that requires 64,000,000 cycles at the input of the counter. With a 450 MHz input, this is accomplished in .142 seconds. Allowing ten times this period insures more than sufficient resolution, and thus the optimal gate time for setting at 450 MHz is around 1.4 seconds. More than this and you are inviting errors due to interference or poor signal coupling. Much less than that and you may not realize all the accuracy of the source. If you are using 900 MHz as your source, you can use half that time. I hope this helps you understand the tradeoffs and design goals of the Scout. It's not an "all things to all people" counter, but instead tailored to a specific purpose. If the unit you have has a problem, please let us rectify it so you can enjoy your Scout as much as all of us enjoy ours. ============================================================================== ****************************************************************************** Document 5 What The Scout Will Count - User Expectations and Reality The purpose of this discussion is concerning the theory of frequency counters and how it relates to their use and user expectations. Frequency counters are often viewed as a magic box with an antenna that when held in the air will quickly read the frequency of just the signal you've been wanting the frequency of. Obviously, this sarcastic scenario is unrealistic, but let's face it - it's just what we wish the counter would do. Let's look at how close we can come to this and why. First, how does the counter work? Simply, the counter counts the number of positive zero crossings of its input signal in a specified period. Thus, if the input signal is a 100 MHz sine wave and the chosen gate period is one second, the counter will count the number of times the input voltage goes from a negative to a positive voltage in one second, and display that as the frequency of the input (cycles per second = Hertz (Hz)). Getting an accurate frequency count depends on the counter seeing only zero crossings due to a single signal. If two or more signals are present at the input to the counter, the voltages of the two signals add and the zero crossings are distorted, resulting in erroneous counts. Exactly how much signal it takes to screw up counting of the desired signal depends on the both the relative amplitudes and frequencies of the signals, but a good rule of thumb is that the desired signal should be 10 to 15 dB higher than all others to get a usable count. If more than one interfering signal is present, the situation gets worse quickly. How does this impact frequency counting in the field? Transmitter sites with many transmitters operating simultaneously can be seen to be a particularly bad choice for the use of a frequency counter. The multitude of signals produce a cacophony of zero crossings that the counter cannot separate single signals from. If you are lucky enough to catch the site when only one transmitter is operating, a counter will read correctly, but this will be the exception. The same conditions apply at cell sites because the control channel as well as numerous individual channel transmitters all operate simultaneously, making successful counting very unlikely. This scenario can be helped by filters if the transmitters happen to be widely spaced in frequency, but this is not often the case. Even if a single transmitter is operating, a high-gain vertical antenna may direct very little radiated energy toward the base of the tower. It seems intuitive that the signal should get stronger as you approach the tower, but in fact you may just be getting further into the null of a very directive antenna. Don't expect to count anything coming from a "dish" antenna - they are very directive and probably operating at a very high frequency above the capability of your counter. Cellular phones can be difficult to count since the phone transmitter power output varies over a wide range under command of the cell site. This makes cellphone range testing very ambiguous and generally unrepeatable. Other pulsed or TDMA (time division multiple access) signals may look like a nice strong signal on the counters level meter, but because the signal actually is only present part of the time, cannot be correctly counted with a typical counter. A good example here is a garage door opener transmitter. TV stations are also usually uncountable because of the AM present and the presence of the aural transmitter carrier which messes up the zero crossings. Counting while in a moving vehicle (or counting a moving emitter) can cause problems due to multipath fading. The brief nulls in the signal caused by this fading my be barely perceptible noise burst on a scanner but chop big holes in the short gate period of a counter and render counts inaccurate. Using antennas larger than a half wavelength long can help this situation since the a longer antenna will no be completely contained in the spatial null. So what CAN you count? Mobile and handheld two-way radios make excellent targets for counting because they are typically the only transmitter operating in a given area and result in a relatively pure signal. These include police, fire, utilities, hams, cellular phones (sometimes), traffic lights, telemetry, etc. Broadcast FM transmitters can also be counted, but it's usually easier to look at the sign on the side of the transmitter shack. Don't be discouraged if you can't count something on demand - there probably just isn't anything to count. I can leave a counter on my workbench for hours without a single hit and know there's no problem with the equipment. Take comfort in knowing all the RFD energy you're not getting irradiated with. ============================================================================== ****************************************************************************** Document 6 PRODUCT PRICE LIST (Prices and Specifications subject to change without notice.) February 2, 1995 MODEL DESCRIPTION PRICE Scout 40 Frequency Recorder $449 ScoutBlaster Scout with accessory pack $850 3300 MiniCounter, 10 Digit LCD $139 M1 MicroCounter,Bargraph,Backlit LCD $249 3000A Plus MultiFunction/RS-232-C Interface $349 3000APlusTCXO +/- .2ppm Timebase Option $449 8040 Bench Multifunction Counter $679 OPTION 1 TCXO90 +/- 0.1 ppm Timebase $135 OPTION 2 OCXO90 +/- 0.05 ppm oven $249 OPTION 3 NiCad90 Battery Pack/Rapid $139 SSB220A SSB/General Purpose RF Bench Counter $399 OPTION 1 TCXO90 +/- 0.1ppm Timebase $135 OPTION 2 OCXO90 +/- 0.05ppm 0-50 C Oven $249 OS456 Computer Scanning Board for PRO2005/6 $299 OS535 Computer Scanning Board for PRO2035 $299 R10 FM Communications Interceptor $359 R20 RF Signal Strength Bargraph $119 DC440 Decoder for CTCSS/DTMF/DCS CI-V $259 NICAD44 Internal Nicad Battery Pack for DC440 $39 APS104 Active Pre-selector $995 CF802 Band Pass Filter/Amplifier,825-845MHz $149 BLP70 70MHz Low Pass Filter $36 BHP800 800MHz High Pass Filter $40 N100 FM Broadcast Band Notch Filter $99 UTC150 Counter Timer Module/Panel Meter/220MHz $99 ANT-PAK1 TA100S, RD27, RD800 save $11 $65 ANT-PAK2 RD27/RD150/RD440/RD800/TA100 Save $15 CC12 Padded Black Vinyl Carry Case $12 CC30 Padded Black Vinyl Carry Case $15 P101 Probe, Low Pass for audio $20 P30 HiZ Probe for Frequency Counter $35 RA-BNC Right Angle BNC $6 TA100S Telescoping Whip Antenna $12 RD27 Rubber Duck Antenna 26MHz-150MHz $29 RD150 Rubber Duck Antenna 144MHz-165MHz $19 RD440 Rubber Duck Antenna 150MHz-550MHz $19 RD800 Rubber Duck Antenna 500MHz-1000MHz $35 DB32 10 Band VHF/UHF, 1.75"" high $29 AC100 Adap. 120VAC, 60Hz to 12VDC 1Amp $39 AC90 Adap. 110VAC, 60Hz input 9VDC 300mA $9 CX12AR RS232-C Interface Converter $99 SPECTRUM for the Scout FCC Database with Scout Upload Utility and Frequency Query $39 OPTOLOG Frequency Data Logging Software for 8040, SSB220, M1, and 3000A. $25 Optoelectronics Inc. 5821 NE 14th Ave. Ft. Lauderdale FL. 33334 (305)771-2050 Fax (305)771-2052 ==============================================================================