廠家: 美國惠普
產(chǎn)生復合信號
選件001為Agilent 8904A增添了內(nèi)部合成器（總計4個），可以調(diào)制通道A，或疊加給出產(chǎn)生復合波形的能力。所有四個合成器是獨立的，具有精確的相位偏移能力。它們在輸出前可進行數(shù)字化相加。此外，選件001能使通道B、C、D以AM、FM、φM、DSBSC(Double Side-Band Suppressed Carrier 雙邊帶抑制載波)或脈沖調(diào)制的方式調(diào)制通道A。
雙輸出
選件002為Agilent 8904A增添另一等同的合成器和浮置的50Ω輸出部分,對于這兩個源,可獨立設定頻率、幅度、波形、相位。在0～359.9°范圍內(nèi)能精確地改變兩合成器間相位關系,分辨率為0.1°。
FM立體聲復合方式
選件001還具有一產(chǎn)生FM立體聲復合信號的方式。該方式中的測試信號有：左=右、左=-右，僅左、僅右只按一次鍵即可選擇測試音頻頻率、組合電平、測試信號方式、導頻音電平等。立體聲分離一般大于65dB。
通信信號
選件001還為Agilent 8904A增添四種序列方式 ：音頻、DTMF、數(shù)字和跳躍（Hop Ram）序列，使得8904A成為通信信號發(fā)送的有力工具。音頻、DTMF方式產(chǎn)生長度高達750個狀態(tài)的單或雙音調(diào)序列；數(shù)字序列方式產(chǎn)生長度高達750個狀態(tài)的單或雙音調(diào)序列；數(shù)字序列方式產(chǎn)生長度高達3000比特的數(shù)據(jù)流，分辨力100μs；跳躍序列方式可構成16種音調(diào)序列，各自具有相關的幅度、頻率、相位值。
快速跳躍
選件003所增加的功能是從外部使通道A在頻率、相位、幅度方面產(chǎn)生跳躍?？蓪⒍噙_16種頻率/相位/幅度狀態(tài)輸入“HopRam”存儲器。為此外部裝置必須對背面板上提供的4bit寬，TTL電平的地址總線尋址?？稍诙讨?0μs的時間內(nèi)邊疆切換相位。
單元間的相位合成
借助選件005，多個Agilent 8904A可進行相位合成，以提供兩個以上的與相位有關的輸出。在該合成方式下，將一個單元規(guī)定為主時鐘，其它的作為從屬時鐘。兩個信號經(jīng)外部低耗功率分配器由時鐘主單元饋至所有的從屬單元。為進行單元合成，經(jīng)前面板或GPIB將相位復位命令發(fā)送給主機8904A。在0.1Hz～100kHz頻率范圍，單元間總的相位誤差大于0.1°或60ns.可合成多達8臺的8904A。
600Ω平衡輸出
選件006將輸出1從50Ω電浮動輸出改變?yōu)樽儔浩黢詈系?00Ω平衡輸出.它可將高功率平衡信號送入600Ω負載。至600Ω的輸出電壓為10V（有效值）。選件006限定輸出1的頻率范圍為30Hz～100kHz。此外，復合波形，如方波、斜波、三角波等都被衰減，直流信號不能經(jīng)由選件006輸出通過。但是，在許多應用中，8904A選件006直接替代了Agilent200CD寬范圍振蕩器。
The HP 8904A Multifunction Synthesizer uses the latest VSLIC technology to create complex signals from six fundamental waveforms. The standard HP 8904A digitally synthesizes precise sine, square, triangle, ramp, white noise, and dc waveforms and routes these signals to a signal output. Option 001 adds three more identical internal synthesizers (channels) which either can modulate the first synthesizer or be summed to the output. Frequency, amplitude, waveform, phase, and destination can be set independently for each synthesizer. Available modulation types for channel A include AM, FM, ØM, DSBSC, and pulse modulation. Option 002 adds a second output, providing a second, separate signal for two-channel applications. Option 003 adds fast hop and digital modulation capability to the HP 8904A. All this unique capability makes the HP 8904A a powerful new tool for demanding applications like VOR, ILS, FM Stereo, and communications signaling.
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The HP 8904A Multifunction Synthesizer delivers synthesizer accuracy, along with six waveforms in a compact, economical package. Broad sinewave frequency coverage from 0 Hz to 600 kHz with 0.1 Hz resolution make the HP 8904A ideal for a number of low-frequency applications. In addition to sinewave generation, the HP 8904A has five other standard functions: square, triangle, ramp, dc, and Gaussian white noise. Of these five, square, ramp, and triangle functions are available from 0 Hz to 50 kHz. All waveform values in the HP 8904A are DIGITALLY calculated in real time by Hewlett Packards Digital Waveform Synthesis IC. The use of this chip results in signals with very well-defined accuracy and exact repeatability.
Option 002 adds a second, identical synthesizer and floating output section to make the HP 8904A TWO synthesizers in one half-rack width measurement. Frequency, amplitude, waveform, and phase can be independently set for each of the two synthesizers.
Although both synthesizers are independent, the relative phase between the two outputs can be controlled precisely. Either synthesizer can be varied in phase from 0 degrees to 359.9 degrees with a resolution of 0.1 degree. Testing phase detectors, servo systems, shaft encoders, sonar, and other phase sensitive two-port devices is easy and accurate with the HP 8904A Option 002.
By adding three more (total of four) internal synthesizers which can modulate or be summed with synthesizer A (channel A), Option 001 is the key to complex signal generation for the HP 8904A Multifunction Synthesizer. All four internal synthesizers can be set to generate different waveforms, frequencies, amplitudes, and phase offsets at the same time. These signals then can be DIGITALLY summed before routing to the output. In addition to summing, Option 001 allows channels B, C, and D to be used as modulation sources for channel A. The allowable modulation types for channel A are: AM, FM, ØM, DSBSC (Double Sideband Suppressed Carrier) and pulse modulation. Using summation and modulation, the HP 8904A Option 001 can generate precise VOR composite, ILS composite, and FM Stereo Multiplex composite signals. Only your imagination limits the possibilities for signal generating with the HP 8904A Multifunction Synthesizer.
In addition to the extra channels, Option 001 also adds three sequence modes to the HP 8904A: tone sequence mode, DTMF sequence mode, and digital sequence mode. These modes make the HP 8904A a powerful tool for generating sequences used in communications signaling. Tone sequence mode allows entry of sixteen unique sine wave tones, each with an "on-time" and "off-time". From these sixteen tones, sequences can be built up to a length of 250 tones. The minimum on and off time duration is 800 µs with 10 µs resolution while the maximum value is 655.35 ms. Digital sequence mode can generate digital bit streams up to 1000 bits in length. Minimum period in the digital mode is 100 µs with 10 µs resolution. On and off "levels" in the digital mode can be set to any value for simulating conventions. For ease of entry, data may be entered in binary, octal, editing features and three control modes: single sequence, continuously repeat sequence, and manual step-through the sequence.
Option 003 adds the ability to hop the HP 8904A in frequency, phase, and/or amplitude. Up to 16 frequency/phase/amplitude states can be entered into the "HOP RAM" memory. To hop, an external device must address the four-bit TTL-level address bus provided on the digital port connector on the rear panel. As the address supplied to the bus is varied, the HP 8904A will hop to the frequency/phase/amplitude state that corresponds to that address of the HOP RAM memory. Fast hop can be performed only on channel A. Phase continuous frequency switching can be done in as little as 8 µs.
