厂家: 美国惠普
产生复合信号
选件001为Agilent 8904A增添了内部合成器（总计4个），可以调制通道A，或叠加给出产生复合波形的能力。所有四个合成器是独立的，具有精确的相位偏移能力。它们在输出前可进行数字化相加。此外，选件001能使通道B、C、D以AM、FM、φM、DSBSC(Double Side-Band Suppressed Carrier 双边带抑制载波)或脉冲调制的方式调制通道A。
双输出
选件002为Agilent 8904A增添另一等同的合成器和浮置的50Ω输出部分,对于这两个源,可独立设定频率、幅度、波形、相位。在0～359.9°范围内能精确地改变两合成器间相位关系,分辨率为0.1°。
FM立体声复合方式
选件001还具有一产生FM立体声复合信号的方式。该方式中的测试信号有：左=右、左=-右，仅左、仅右只按一次键即可选择测试音频频率、组合电平、测试信号方式、导频音电平等。立体声分离一般大于65dB。
通信信号
选件001还为Agilent 8904A增添四种序列方式 ：音频、DTMF、数字和跳跃（Hop Ram）序列，使得8904A成为通信信号发送的有力工具。音频、DTMF方式产生长度高达750个状态的单或双音调序列；数字序列方式产生长度高达750个状态的单或双音调序列；数字序列方式产生长度高达3000比特的数据流，分辨力100μs；跳跃序列方式可构成16种音调序列，各自具有相关的幅度、频率、相位值。
快速跳跃
选件003所增加的功能是从外部使通道A在频率、相位、幅度方面产生跳跃。可将多达16种频率/相位/幅度状态输入“HopRam”存储器。为此外部装置必须对背面板上提供的4bit宽，TTL电平的地址总线寻址。可在短至20μs的时间内边疆切换相位。
单元间的相位合成
借助选件005，多个Agilent 8904A可进行相位合成，以提供两个以上的与相位有关的输出。在该合成方式下，将一个单元规定为主时钟，其它的作为从属时钟。两个信号经外部低耗功率分配器由时钟主单元馈至所有的从属单元。为进行单元合成，经前面板或GPIB将相位复位命令发送给主机8904A。在0.1Hz～100kHz频率范围，单元间总的相位误差大于0.1°或60ns.可合成多达8台的8904A。
600Ω平衡输出
选件006将输出1从50Ω电浮动输出改变为变压器耦合的600Ω平衡输出.它可将高功率平衡信号送入600Ω负载。至600Ω的输出电压为10V（有效值）。选件006限定输出1的频率范围为30Hz～100kHz。此外，复合波形，如方波、斜波、三角波等都被衰减，直流信号不能经由选件006输出通过。但是，在许多应用中，8904A选件006直接替代了Agilent200CD宽范围振荡器。
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.
