OPERATION Figure 1 shows a block diagram of the chip. Also shown in Figure 1 are the required external components. Since switched-capacitor filters are used on the chip, the input speech signal must first be filtered by an anti-aliasing one-pole low pass filter before it is applied to the Audio input pin. The filter 3dB break point, which is determined by the product of C1 and R1 plus the output impedance of the audio source, should be less than 20KHz. This filter is required only if high frequency noise is present at the input. To maintain an output signal to noise ratio of 40dB, any unwanted signal higher than 3.5KHz contained in the speech input must be filtered to 40dB below the nominal speech input level, due to the fact that the on-chip modulator is switched at 3.5KHz. The on-chip double sideband modulator can be turned on or off by asserting the SCRAMBLE input pin. The 3.5KHz switching frequency of the modulator is generated by divid ing the output of the oscillator by 1024. The modulator output contains two sidebands centered at the suppressed switching frequency of 3.5KHz. The upper sideband is attenuated by a 4th order Butterworth lowpass filter. The filter, consisting of two biquad switched capacitor filters in cascade, is clocked at 111.9KHz. The inverted input speech spectrum appears at the filter output, and is available at the Audio Output pin. The filter output circuit is designed to drive a maximum capacitive load of 5pf in parallel with a minimum resistance of 15K ohms. A parallel resonant crystal oscillator is employed in the device. The parallel resonant crystal should have a maximum series resistance of 150 ohms with a shunt capacitance of 5pf. To insure reliable oscillator performance, the components shown connected to XTAL pins 14 and 12 in Figure 1 should be used. 'Stresses above those listed may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other condition above those indicated in the operational sections of this specifications is not implied. NOTE: When powering this device from laboratory or system power supplies, it is important that the Absolute Maximum Ratings not be exceeded or device failure can result. Some power supplies exhibit voltage spikes or "glitches" on their outputs when the AC power is switched on and off. In addition, voltage transients on the AC power line may appear on the DC output. If this possibility exists, it is suggested that a clamp circuit be used. 10/85-5M STANDARD MICROSYSTEMS ר ©1985 STANDARD MICROSYSTEMS CORP. Circuit diagrams utilizing SMC products are included as a means of illustrating typical semiconductor applications, consequently complete information sufficient for construction purposes is not necessarily given The information has been carefully checked and is believed to be entirely reliable. However, no responsibility is assumed for inaccuracies. Furthermore, such information does not convey to the purchaser of the semiconductor devices described any license under the patent rights of SMC or others. SMC reserves the right to make changes at any time in order to improve design and supply the best product possible. I am pleased to announce the availability of the COM9046 Data sheet. The release of the COM9046 voice Scrambler/Descrambler comes at a time when the need for privacy in voice communication systems is exacerbating. At the present time, there does not exist on the market a comparable product in the same price range, and that is the reason why the COM9046 is creating so much interest. For your convenience, I have listed below the small quantity pricing for the COM9046 in plastic. Please contact your regional managers for production volume pricing. In addition, please look for a series of Technical Sales bulletins on the MX 340 M MOTOROLA Motorola's DVP Digital Voice Protection System provides the user with the highest level of voice security commercially available today. To an unauthorized listener, a DVP radio transmission is totally unintelligible. Yet when this signal is properly decoded by a DVP receiver, clear audio comes through, providing the user with high intelligibility and excellent voice recognition. To achieve the Digital Voice Protection System's high level security, a two step technique is utilized. First, regular speech is converted to digital speech using Continuously Variable Slope Delta Modulation (CVSD). This output is then scrambled through a highly sophisticated multi-register non-linear combiner algorithm. The resultant transmission contains no voice components and sounds like constant level random white noise. Through the use of this digital scrambling technique, a huge number of unique and statistically unrelated codes are made available to the user2.36 x 10" (2,360,000,000,000,000,000,000). Any one of these codes can be electronically loaded into the secure memory of a DVP radio using the external Code Inserter. The code information contained in the memory of each radio and the Code Inserter cannot be recalled for display and these units will not reveal the code which is in use in a system. Thus, the DVP radio system makes it possible to restrict code information to a limited number of authorized individuals. The MX300 series Digital Voice Protection Handie-Talkie radio belongs to the most advanced portable FM radio family available today. Its modular construction and extensive use of custom hybrid circuitry reflects the latest achievements in microelectronic technology. These techniques assure the ultimate in reliability, ease of maintenance and systems flexibility. DVP Digital Voice Protection Systems Multi-Register Non-Linear Combiner Code Algorithm provides 2.36 x 102 user programmable codes. The coding algorithm and an incredibly large number of unique codes provide a very high level of security against unauthorized listeners, including more technically sophisticated eavesdroppers. All of the codes are unique and statistically unrelated. Only one code out of 2.36 x 102 possibilities will produce an intelligible output. There are no families of codes which are capable of providing a partially decoded output for similar codes. Random Code Key Initialization occurs every time the transmitter is keyed. This random initialization provides increased security since the system will not reset its coding algorithm to the same place at the beginning of each transmission, but will initiate its coding process at a new starting point instead. Self Synchronizing decoding eliminates delays at the beginning of transmissions or delays in system recovery after multipath or weak signal fades. Since no preamble is required, there are no delays or loss of information at the beginning of a transmission. In addition, a coded message will not be lost because no synchronization signal is received. Internal Secure Electronic Code Storage within the radio unit eliminates code switches and does not reveal any knowledge of the code key by external visual or electronic probing. Consequently, code information is restricted to a limited number of authorized personnel. Code Insertion into DVP radios is an operation which can be performed quickly and easily. The user can insert a new code into a DVP radio in a matter of seconds by connecting a DVP Code Inserter to the radio and pressing the code insert button. There are no mechanical keys required or switches which have to be set manually. Continuously Variable Slope Delta Modulation, operating at a 12 Kilobit/ second voice sample rate, is used to convert normal speech to digitized speech prior to scrambling and then back to normal speech after the receiver signal has been decoded. This A/D conversion technique, in combination with a new radio design incorporating optimized circuitry for digital voice transmission, coding and audio response, assures excellent voice recognition and high intelligibility. Automatic Code Destruction With Power Loss provides added code security. If someone attempts to tamper with a DVP radio and removes the code module, the code which it contains will be destroyed. To allow the user to change portable batteries, a time delay has been incorporated into the design of this feature to preserve code during this operation. Systems Features Complete system design capability Automatic or manual transmitter Private-Line Squelch compatible in Squelch tail elimination in the clear Utilizes narrow band RF channels |