可调接收音频滤波器 27 CHAPTER Adjustable Receiver Audio Filter
本章要点：除了 IF 侧的滤波手段之外，FTX-1 还在 AF（音频）级提供了可调接收音频滤波器，可对音频低端和高端分别独立裁 剪。本章说明 LCUT / HCUT 频率与斜率的设置方法、按模式分别保存的默认值，以及与接收音质（AF TREBLE / MIDDLE TONE / BASS GAIN）调整之间的区别和配合使用方式。
27-1 Adjustable Receiver Audio Filter · 可调接收音频滤波器
FTX-1 内置可调接收音频滤波器，可对音频的低端和高端 The FTX-1 incorporates an adjustable receiver audio filter, 范围分别进行精确控制。 that affords precision control of the lower and upper audio 1. 按住 [FUNC] 旋钮。 ranges independently. 2. CW 模式选择 [CW SETTING]，其他模式选择 [RADIO 1. Press and hold the [FUNC] knob. SETTING]。 2. Select [CW SETTING] for CW mode and [RADIO 3. 选择要设置的模式和菜单项（见下表）。 SETTING] for other modes. 3. Select the Mode and Menu Item you want to set (see 4. 旋转 [FUNC] 旋钮，或触摸数值两侧的 "<" / ">"， table below). 按需调整接收音频响应。
4. Rotate the [FUNC] knob, or touch "<" or ">" on either 5. 按 [FUNC] 旋钮，或等待约 3 秒保存设置。 side of the value to adjust the receiver audio response 6. 按几次 [BACK] 键返回正常操作。 as desired. 5. Press the [FUNC] knob, or wait for about 3 seconds to save the setting. 6. Press the [BACK] key several times to return to normal operation.
表 27-1 可调接收音频滤波器菜单项与默认值 Table 27-1 Adjustable receiver audio filter menu items and defaults
菜单组 模式 菜单项 可选值 默认值 Menu group Mode Menu item Available values Default
RADIO SETTING SSB LCUT FREQ （ OFF / 100 Hz – 1000 Hz 50 Hz 步进） 100 Hz
LCUT SLOPE 6 dB/oct / 18 dB/oct 6 dB/oct
HCUT FREQ （ 700 Hz – 4000 Hz 50 Hz 步进）/ OFF 3000 Hz
HCUT SLOPE 6 dB/oct / 18 dB/oct 6 dB/oct
RADIO SETTING AM LCUT FREQ （ OFF / 100 Hz – 1000 Hz 50 Hz 步进） OFF
LCUT SLOPE 6 dB/oct / 18 dB/oct 6 dB/oct
HCUT FREQ （ 700 Hz – 4000 Hz 50 Hz 步进）/ OFF OFF
HCUT SLOPE 6 dB/oct / 18 dB/oct 6 dB/oct
RADIO SETTING FM LCUT FREQ （ OFF / 100 Hz – 1000 Hz 50 Hz 步进） 300 Hz
LCUT SLOPE 6 dB/oct / 18 dB/oct 18 dB/oct
HCUT FREQ （ 700 Hz – 4000 Hz 50 Hz 步进）/ OFF 3000 Hz
HCUT SLOPE 6 dB/oct / 18 dB/oct 18 dB/oct
RADIO SETTING DATA LCUT FREQ （ OFF / 100 Hz – 1000 Hz 50 Hz 步进） 100 Hz
LCUT SLOPE 6 dB/oct / 18 dB/oct 18 dB/oct
HCUT FREQ （ 700 Hz – 4000 Hz 50 Hz 步进）/ OFF 3200 Hz
HCUT SLOPE 6 dB/oct / 18 dB/oct 18 dB/oct
RADIO SETTING RTTY LCUT FREQ （ OFF / 100 Hz – 1000 Hz 50 Hz 步进） 300 Hz
LCUT SLOPE 6 dB/oct / 18 dB/oct 18 dB/oct
HCUT FREQ （ 700 Hz – 4000 Hz 50 Hz 步进）/ OFF 3000 Hz
HCUT SLOPE 6 dB/oct / 18 dB/oct 18 dB/oct
CW SETTING CW LCUT FREQ （ OFF / 100 Hz – 1000 Hz 50 Hz 步进） 250 Hz
LCUT SLOPE 6 dB/oct / 18 dB/oct 18 dB/oct
HCUT FREQ （ 700 Hz – 4000 Hz 50 Hz 步进）/ OFF 1200 Hz
HCUT SLOPE 6 dB/oct / 18 dB/oct 18 dB/oct
各滤波设置按工作模式分别保存（SSB、AM、FM、 The filter settings are stored separately for each operating DATA、RTTY 与 CW 各自独立），因此 CW 抄收时使用 mode (SSB, AM, FM, DATA, RTTY and CW), so a narrow 的窄带设置不会影响 FM 使用的宽带设置。 setting used for CW copying will not affect the wide setting used for FM.
HAM 实战 · LCUT / HCUT 的实战用法 FIELD NOTE
AF 级的 LCUT / HCUT 是在音频上再裁一刀，和 IF 侧的 CONTOUR、NOTCH、DNF 作用位置不同，可以叠加使用（社区经 验）： ① SSB 拥挤频段：把 LCUT FREQ 提到 300 Hz 左右、SLOPE 用 18 dB/oct，可以明显压掉邻台的隆隆声和低频噪声；弱信号 DX 时则降回 100 Hz 保留更多语音能量。 ② SSB Contest 抄收：HCUT FREQ 收到 2400 Hz 附近能削掉高端嘶声，代价是声音发闷，需要在"听得清"与"听得舒服"之间 取舍。 ③ CW：默认 LCUT 250 Hz / HCUT 1200 Hz 已经是很舒服的窗口，遇到极拥挤时收窄到 100 Hz 步进细调即可，不必一开 始就动 slope。 ④ AM/FM 广播监听或本地中继守听：这一组默认较宽（AM 默认 LCUT OFF / HCUT OFF），想提升语音可懂度再加 LCUT 300 Hz 即可。 注意 slope 选 18 dB/oct 时截止更陡，但容易在截止点附近产生"闷罐感"，弱信号下推荐 6 dB/oct。 The AF LCUT/HCUT filters work at a different stage from the IF CONTOUR, NOTCH and DNF functions and can be combined with them (community-reported). Raise LCUT to about 300 Hz with 18 dB/oct on crowded SSB bands, and return to 100 Hz for weak-signal DX. Narrow HCUT for contest copying at the cost of a muffled sound. The 18 dB/oct slope cuts harder but can sound boxy; 6 dB/oct is gentler for weak signals.
27-2 Change the Sound Quality of the Received Audio · 接收音质调整
可以按自己的喜好分别调整接收音频的高音、中音和低 You can change each of the high, mid, and low frequencies 音。可按每个模式分别设置。 of the received audio to your liking. It can be set for each 1. 按住 [FUNC] 旋钮。 mode. 2. CW 模式选择 [CW SETTING]，其他模式选择 [RADIO 1. Press and hold the [FUNC] knob. SETTING]。 2. Select [CW SETTING] for CW mode and [RADIO SETTING] for other modes. 3. 选择要设置的模式和菜单项（见下表）。
3. Select the Mode and Menu Item you want to set (see 4. 旋转 [FUNC] 旋钮，或触摸数值两侧的 "<" / ">"，
table below). 按需调整接收音频响应。
4. Rotate the [FUNC] knob, or touch "<" or ">" on either 5. 按 [FUNC] 旋钮，或等待约 3 秒保存设置。 side of the value to adjust the receiver audio response 6. 按几次 [BACK] 键返回正常操作。 as desired. 5. Press the [FUNC] knob, or wait for about 3 seconds to save the setting. 6. Press the [BACK] key several times to return to normal operation.
表 27-2 接收音质调整菜单项 Table 27-2 Received audio sound quality menu items
菜单组 适用模式 菜单项 可选值 默认值 Menu group Mode Menu item Available values Default
RADIO SETTING SSB / AM / FM / DATA / AF TREBLE GAIN高音范围设置 -20 – 10 0 RTTY AF MIDDLE TONE GAIN中音范围设置 -20 – 10 0
AF BASS GAIN低音范围设置 -20 – 10 0
CW SETTING CW AF TREBLE GAIN高音范围设置 -20 – 10 0
AF MIDDLE TONE GAIN中音范围设置 -20 – 10 0
AF BASS GAIN低音范围设置 -20 – 10 0
技术提示 / TIP
LCUT / HCUT 是"裁掉"（滤波），AF TREBLE / MIDDLE TONE / BASS GAIN 是"增减"（音调），两者是不同层的东西，别 混为一谈：想去掉某个频段的干扰用 LCUT / HCUT，想让整体声音更亮或更厚用 AF 三项 GAIN。默认全部为 0，建议先单独 调滤波器，音质 GAIN 保持 0，等确认滤波器已到合适位置后再做音色微调。 LCUT/HCUT are cut-off filters, while AF TREBLE / MIDDLE TONE / BASS GAIN are tone controls. Use the filters to remove interference and the tone controls to shape the overall sound. All three AF gains default to 0.