IC-7851_broch_USA.pdf

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1、THE TRANSCEIVER Solid Design Basics and HF Expertise Raising the Bar Contesters and DXers are always looking for that competitive edge to magically pull out the weak signal that is either the rare country or multiplier they need to climb up the list. Larger antennas, higher gain pre-amps and other d

2、evices in line are great. However, what happens inside the radio with all those signals coming down your feedline can defeat all your efforts. With the design of the IC-7851, Icom s engineers focused on a new Local Oscillator (LO) that drastically reduces the phase noise. As a result of this design,

3、 the purity of the LO achieves a Reciprocal Mixing Dynamic Range (RMDR) of 110dB. In addition to the incredibly clean LO allowing you to hear the weak signals, the new spec- trum scope design enables you to see the weak ones! Faster processors, higher input gain, higher display resolution and a clea

4、ner signal from the receiver s LO will give you a new window into the RF world. Adding this performance and functionality for both receivers give you a dual scope portal. THE TRANSCEIVER 1 Competitive Advantage: Reciprocal Mixing Dynamic Range R e c i p r o c a l M i x i n g D y n a m i c R a n g e

5、RMDR: 110dB Raising the Bar IC-7851IC-7800 IC-7851IC-7800 Design advances developed by the Icom HF engineers for the Local Oscillator (LO) enable the IC-7851 to set a new benchmark for amateur radio receivers. The goal was to dramatically reduce the phase noise that degrades the target signal due to

6、 the sum of the entire signal pres- ent. The result was a RMDR of 110dB*. Below is a comparison of the improvement over the IC-7800. RMDR RMDR (Reciprocal Mixing Dynamic Range) is the relative level of an undesired signal, offset “n” kHz from the RX passband, which will raise noise floor by 3 dB. Th

7、e local oscillator phase noise will mix with strong unwanted signals and unavoidably generate noise which masks a wanted signal. Breaking the boundaries of traditional designs, the IC-7851 employs a Direct Digital Synthesizer (DDS) along with a Phase Locked Oscillator for the LO. The C/N ratio excel

8、s beyond the IC-7800 and other similar class HF transceivers. This design significantly reduces noise components in both receive and transmit signals. Improved Phase Noise Characteristics Phase noise is coherent in radio circuit design and the new LO design introduced in the IC-7851 makes some major

9、 breakthroughs while utilizing the 64MHz, up-conversion receiver design introduced in the IC-7800. An impressive 20dB improvement is seen with the IC-7851s 10 kHz measure- ment and more than 30dB improvement at a 1 kHz measurement in com- parison to the IC-7800. Phase Noise Characteristics Compariso

10、ns Receiving Frequency: 14.2 MHz Mode: CW 1st LO frequency: 78.655 MHz LO C/N Characteristics Comparisons Crystal Clear LO (Local Oscillator) Design 1.2kHz Optimum Roofing Filter Optimum Roofing Filter Characteristic Diagram Optimum Roofing Filter Despite the trend to switch to a down conversion or

11、a hybrid conversion receive design, Icom believes in the solid performance of the up-conversion design. In an up-conversion receiver, suppression of image interference and reduce distortion from electric components is easily overcome. A flat consistent performance is delivered over a wider frequency

12、 range. The IC-7851 introduces a new 1.2kHz Optimum Roofing Filter, greatly improving the in-band adjacent signal performance. This newly devel- oped filter overcomes the gap of a narrower roofing filter in an up-conversion receiver. * At a 1kHz offset frequency Receiving frequency: 14.2 MHz Mode: C

13、W, IF BW: 500 Hz Roofing Filter IC-7800 = 3 kHz, IC-7851 = 1.2 kHz RMDR Comparison RMDR(dB) IC-7851 IC-7800 1kHz 110 78 2kHz 116 87 10kHz 121 106 20kHz 124 112 1 kHz10 kHz100 kHz1 MHz100 Hz10 MHz -160 -150 -140 -130 -120 -110 -100 -90 -80 Frequency Offset -70 dBc/Hz-70 dBc/Hz 1 kHz10 kHz100 kHz1 MHz

14、100 Hz10 MHz Frequency Offset Receiving Frequency: 14.2 MHz Mode: CW 1st LO frequency: 78.655 MHz SPAN = 20 kHz, RBW = 30 Hz, VBW = 10 Hz -160 -150 -140 -130 -120 -110 -100 -90 -80 -10 0 -20 -30 -40 -50 -60 -70 -80 -90 -100 -10 0 -20 -30 -40 -50 -60 -70 -80 -90 -100 2 Twice the Speed, Sensitivity, R

15、esolution and More Control Scope DSP TMS320C6745 by Texas Instruments 32-bit floating point 2250 MFLOPS 370 MHz clock speed Mini spectrum scope and audio scopeMini dual spectrum scope and audio scope Following the design linage of the IC-7800, the IC-7851 uses a dedicated DSP unit for the Fast Fouri

16、er Transform (FFT) spectrum. The 2250 MFLOPS DSP processor enables a new dual scope function and signifi- cantly faster sweep speeds and better accuracy than in the IC-7800. S p e c t r u m S c o p e Improved Spectrum Scope The waterfall display captures signal strengths over time. This allows you t

17、o see signals that may not be apparent on a normal scope. Addi- tionally, the combination of the scope attenuator and the wide screen mode gives you a better view of weaker signals as band conditions change. For the ultimate scope enhancement, the IC-7851 has a digital video interface (DVI-I) for a

18、larger display. High Resolution Spectrum Waterfall Display By connecting a human interface device (such as a USB mouse, trackball or touchpad) to the USB port on the rear panel, you gain control over the spec- trum display pointer for “Click-and-Listen” receiver control. Fix/Center mode, sweep speed

19、 and other settings are controllable. Click Control Audio Scope Function The audio scope simultaneously shows an oscilloscope and FFT for receive and transmit audio. Adjust your transmit audio by watching your compressor level, equalization and mic gain settings to give you the audio you want for SS

20、B. The oscilloscope shows the CW waveform. On receive, you can see the power of your filtering by watching filtering adjustments take out interfering signals including filter width and notch filter placement. The processing power in the IC-7851 allows for dual mini band scopes as well as the audio s

21、cope. Span Width Resolution *1 Sweep Speed Display Dynamic Range Noise Floor Level IC-7851 5kHz1000kHz 1 pixel minimum *2 29.3 frames/Sec *3 100dB 30dB IC-7800 5kHz1000kHz 20 pixels minimum *4 4 frames/Sec *3 80dB 19dB *1 Number of dots shown at the 60 dB level, when receiving a signal. *2 SPAN = Mo

22、re than 20 kHz, SPEED = Slow *3 SPAN = Less than 20 kHz, SPEED = Fast *4 SPAN = 500 kHz, SPEED = Slow Spectrum scope with waterfall (wide screen setting) Attenuator: 0 dB, 10 dB, 20 dB and 30 dB FFT scope with waterfall and FFT scope without waterfall Waveform color and drawing (outline or fill) set

23、tings for the FFT scope Level: 0dB, 10 dB, 20 dB and 30 dB Sample rate: 1ms/Div, 3ms/Div, 10ms/Div, 30ms/Div, 100ms/Div and 300ms/Div, 5 Div width Waveform color setting Dual scope example (Vertically aligned)Dual scope example (Horizontally aligned) While you can watch both receivers on the scope o

24、f the IC-7800, within the limits of the scope bandwidth, the IC-7851 introduces the new dual scope the ability of watching both receivers in separate spectrum scopes. The dual scope function is vital for watching for multipliers or band openings in contests, or working all bands/modes on a DXpeditio

25、n. Dual Scope Function Scope Comparison Specifications for the audio scope Specifications for the oscilloscope Left click to change operating frequency Click a button (either left or right) and move right or left side on the screen to increase or decrease the operating frequency (similar to rotating

26、 the main dial) Right click to temporarily change the receive frequency. Release the mouse button to return. 3 REF 0.0 dBmMKR 14.16 MHzDL 30.0 dBm 10 dB/ 0dB 8.73dBm*A_Write NormB_Blank Norm START 0 HzSTOP 30.00 MHz RBW 300 kHzVBW 300 kHzSWP 200ms ATT 10 dB MARKER 14 . 16 MHz Premium components yiel

27、d premium performance The IC-7851 continues the +40dBm, 3rd order intercept point and 110dB receiver dynamic range benchmark set by the IC-7800. To achieve this superb receiver performance, the entire analog circuitry and components have been re-engineered to match the DSP units. A newly designed LO

28、 amplifier generates high output while keeping flat frequency characteris- tics over a 60MHz wide range. BPF unit Triple DSP Power Digi-Sel Preselector The IC-7851 incorporates high-grade, long-term reliable mechanical relays rather than PIN diodes for switching the Band Pass Filters (BPF). This dep

29、loyment of relays re- moves secondary distortion products from the primary stage of signal processing. 1.2kHz Optimum Roofing Filter 3, 6, 15kHz High-Spec 1st IF filters Automatic Preselector High Performance OCXO Unit The IC-7851 uses the OCXO (Oven Control Crystal Oscillator) unit which is stable

30、to within 0.05ppm at 0C to 50C. This specification means that even on the 50MHz band, frequency error is less than 2.5Hz! In addition, a 10MHz refer- ence frequency can be input and output for accurate tuning. OCXO unit PA unit and heat sink The push-pull power a m p l i fi e rs u s i n g power MOS-

31、FETs work on 48V DC. They provide a pow- erful 200W output power at full duty cycle and low transmit intermodulation. An effective cooling system maintains internal temperatures within a safe range and prevents thermal runaway. 200W Output Power at Full Duty Cycle Solid Aluminum Main Dial Knob B a s

32、 i c F u n c t i o n s The main dial tuning knob is pure functional beauty. Machined from a solid aluminum block, the main dial tuning knob gives you a solid operational feel. The diamond engraved accents are cosmetic perfection expected only from a radio of this caliber. Dynamic Range (dB) Spacing

33、Roofing Filter Bandwidth IC-7851 1kHz 100 99 15kHz 1.2kHz 2kHz 101 105 5kHz 104 111 20 kHz 114 113 Dynamic Range Characteristics Three separate 24-bit AD/DA converters and dedicated DSP processors are at the heart of the IC-7851. With one AD/DA and DSP dedicated to the spectrum scope and two 24-bit

34、AD/DA and DSP chips for the receivers and transmit circuits, there is plenty of DSP power for the most demanding RF environment. The IC-7851 has multiple AGC loops. The AGC voltages detected in front of and behind the digital IF filter in the DSP unit. The first AGC loop prevents saturation of the 1

35、st IF amplifier. The other AGC loop detects the AGC voltage at the digital IF filter output which has only passed the intended signal and draws the full potential from the digital IF filter. Combining the digital IF filter, manual notch, and the 1st IF stage, these are all controlled by the DSP unit

36、. 110dB of ultra wide dynamic range in the receiver means the IF amplifier is distortion free from strong signals. Dual AGC Loops Simple receiver system configuration is the best way to eliminate sources of the spurious signals and distortion from transceivers. The IC-7851 uses a double conversion s

37、ystem com- posed of a D-MOS FET 1st mixer and image rejection mixer for the 2nd stage. The 1st mixer stage is driven with a signal from the high-drive Local Oscillator with excellent C/N. The image rejection mixer for the 2nd stage reduces signal distortion through IF processing and provides a high-

38、fidelity signal to the DSP unit. This system provides wide dynamic range, reducing the dis- tortion from strong signals and lower intermodu- lation. Image Rejection Mixer BPF AGC Loop line A/D D/A AGC DET AGC DET AGC DET AGC DET AGC DET AGC DET 2nd Mixer (Image Rejection Mixer)Receiver DSP Unit AMPA

39、MPAMP IF AMP IF AMP IF AMP IF AMP IF AMP IF AMP IF AMP IF AMP IF AMP 90 degrees Phase shifter 90 degrees Phase shifter 90 degrees Phase shifter Transmit/ Receiver DSP (left) and Receiver DSP (right) ADSP-21489 by Analog Devices 32-bit floating point DSP 2400 MFLOPS 393 MHz clock speed The preselecto

40、r w o r k s b e t w e e n 1.5MHz and 30MHz and rejects distortion components derived from out of band interference such as multi-multi operation or strong broadcast sta- tions. It automatically tracks the intended signal keeping the preselectors bandwidth centered on the operating frequency. The cen

41、ter frequency of the preselector is manually adjustable from the DIGI-SEL tuning knob on the front panel. Intercept Point +40dBm IP3 Dynamic range 110dB Antenna Terminal input Receiver output Noise Floor level +40dBm IP3 (3rd Order Intercept Point) BPF Switching: Mechanical Relays Three high-spec 1s

42、t IF “Roofing” filters plus the new 1.2kHz Optimum Roofing Filter allow only signals within the filter passband to the 1st IF amplifier stage. You can select the filter width from 15kHz, 6kHz, 3kHz and 1.2kHz, depending on your operating mode. (FM mode is fixed at 15kHz) Four 1st IF “Roofing” Filter

43、s Dynamic Range (typical) Automatic Preselector bandwidth characteristics At 14 MHz band 4 RTTY mode display RTTY, PSK31 as well as the new PSK63 modes are available at your fingertips without the use of a computer. The built-in Modulator/Demodulators are activated by via the radios functions button

44、s or an optional USB keyboard. TX memories make contacts a snap and communications logs can be stored on an SD memory card. SD Memory Card Slot The DSP controlled RF speech compressor provides additional punch while maintaining the original tone quality of the operator. The IC-7851 utilizes the 32-b

45、it DSP for the RF speech compres- sor, providing the maximum punch without the fuzzy sound. Its great for breaking through the noise and hash to complete the QSO. Operational functionality for the most advanced operators Digital RF Speech Compressor Improved Automatic Antenna Tuner Save operator pro

46、files, digital voice keyer, CW memory keyer, RTTY/PSK logs, IC-7851 “Screen Shots” and various other operational settings to your SD Memory card. The automatic antenna tuner utilizes tune- setting memories to record the best tuner configuration for the lowest SWR. This allows a faster response time

47、when jumping bands or moving around in the same band. Filter preset screen Recorded list display Digital Voice Recorder The digital voice recorder captures both receive and transmit audio to your SD or USB storage de- vices. Up to 9 hours of continuous audio recording is possible with 2 GB of storag

48、e. Record your QSO with a rare entity or record your operating time in a contest. Operating frequency, mode, S-meter and output power are automatically captured. RTTY/PSK31 and PSK63 SD Memory Card Slot New Auto Digital Noise Blanker While most noise blanker reduces pulse type noise, the IC-7851 int

49、roduces a new automatic digital noise blanker circuit. While using the 15/9/6kHz roofing filters, the digital noise blanker gives you full control. When the 1.2kHz Optimum Roofing Filter is activated, the best blanking level is automatically selected. Ad- ditional adjustments allow you to tweak the threshold level, blank time and attenuation level parameters. Variable Level Noise Reduction The digital noise reduction separates a target signal from noise components and noise sup- pression level is variable in 16 -steps, depending on the noise l